Passive optical network system, optical line terminal, and optical network unit

ABSTRACT

The present disclosure relates to passive optical network (PON) systems, an optical line terminal (OLT), and an optical network unit (ONU). One example PON system includes an OLT and at least two ONUs, and the OLT and the ONUs exchange data on one downstream channel and two upstream channels. The OLT sends downstream data to each ONU on the downstream channel, where the downstream data includes an upstream bandwidth grant which is used to control the ONU to send upstream data. Each ONU receives the downstream data on the downstream channel, and sends the upstream data on a first upstream channel or a second upstream channel based on the upstream bandwidth grant included in the downstream data. The OLT receives, on the first upstream channel and the second upstream channel, the upstream data sent by each ONU.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/418,886, filed on May 21, 2019, which is a continuation ofInternational Application No. PCT/CN2016/106919, filed on Nov. 23, 2016.All of the afore-mentioned patent applications are hereby incorporatedby reference in their entireties.

TECHNICAL FIELD

This application relates to the optical communications field, and inparticular, to a passive optical network (PON) system, an optical lineterminal (OLT), and an optical network unit (ONU).

BACKGROUND

A passive optical network (PON) is a point-to-multipoint networktopology structure, and usually includes an optical line terminal (OLT)in a central office, a plurality of optical network units (ONU) at auser end, and an optical distribution network (ODN) located the OLT andthe ONU.

In a PON system, a newly added ONU needs to complete registration andactivation at an OLT before sending an upstream service data to the OLTover an upstream channel. In an Ethernet passive optical network (EPON)system, an OLT receives, by creating a quiet zone, a registrationresponse packet sent by a newly added ONU over an upstream channel,allocates a logical link identifier (LLID) to the newly added ONU basedon a Media Access Control (MAC) address carried in the registrationresponse packet, and completes ranging of the newly added ONU. In agigabit-capable passive optical network (GPON) system, an OLT receives,by creating a quiet zone, a registration response packet sent by a newlyadded ONU, allocates an ONU ID based on a serial number (SN) carried inthe registration response packet, and further completes ranging of thenewly added ONU.

After being registered, a registered ONU sends upstream service data toan OLT over an upstream channel in a Time Division Multiple Accessmanner (TDMA) and based on an upstream sending timeslot allocated by theOLT, to prevent upstream service data sent by different ONUs fromconflicting with each other on the upstream channel. In addition, toavoid a conflict between a registration response packet and the upstreamservice data on the upstream channel, during registration of a newlyadded ONU, the OLT stops providing a bandwidth grant for a registeredONU, that is, the registered ONU stops sending upstream service data.

In the PON system, the registered ONU needs to send the upstream servicedata only after the quiet zones ends. As a result, the upstream servicedata is sent with a relatively large delay, and a system delayrequirement of a low-delay service cannot be satisfied.

SUMMARY

To resolve the problem that because a registered ONU needs to sendupstream service data only after a quiet zone ends, the upstream servicedata is sent with a relatively large delay and a system delayrequirement of a low-delay service cannot be satisfied, embodiments ofthis application provide a PON system, an OLT, and an ONU. The technicalsolutions are as follows:

According to a first aspect, a PON system is provided. The systemincludes an OLT and at least two ONUs, the OLT is connected to each ONUby using an ODN, and the OLT and the at least two ONUs exchange data onone downstream channel and two upstream channels;

the OLT sends downstream data to each ONU on the downstream channel,where the downstream data includes an upstream bandwidth grant, and theupstream bandwidth grant is used to control the ONU to send upstreamdata;

the ONU receives the downstream data on the downstream channel, andsends the upstream data on a first upstream channel or a second upstreamchannel based on the upstream bandwidth grant included in the downstreamdata; and

the OLT receives, on the first upstream channel and the second upstreamchannel, the upstream data sent by each ONU, where

a registration function is disabled on the first upstream channel, theregistration function is enabled on the second upstream channel, and theregistration function is used to register an unregistered ONU.

Different from the prior art in which data is exchanged on only onedownstream channel and one upstream channel in the PON system, in thisembodiment, the downstream channel, the first upstream channel on whichthe registration function is disabled, and the second upstream channelon which the registration function is enabled are configured in the PONsystem. In this way, after the OLT sends the downstream data to each ONUon the downstream channel, the ONU can send upstream service data andperform ONU registration on different upstream channels based on theupstream bandwidth grant included in the downstream data, to preventregistration of the ONU from affecting sending of the upstream servicedata, and satisfy a system delay requirement of a low-delay service.

In a possible design, the downstream data includes a first upstreambandwidth grant and a second upstream bandwidth grant, the firstupstream bandwidth grant is used to control the ONU to send upstreamdata on the first upstream channel, and the second upstream bandwidthgrant is used to control the ONU to send upstream data on the secondupstream channel.

In a possible design, the OLT generates the first upstream bandwidthgrant and the second upstream bandwidth grant, and multiplexes the firstupstream bandwidth grant and the second upstream bandwidth grant toobtain the multiplexed upstream bandwidth grant; and the ONUdemultiplexes the received upstream bandwidth grant to obtain the firstupstream bandwidth grant and the second upstream bandwidth; and sendsupstream data on the first upstream channel based on the first upstreambandwidth grant, and sends upstream data on the second upstream channelbased on the second upstream bandwidth grant.

In this embodiment, the OLT generates the first upstream bandwidth grantand the second upstream bandwidth grant respectively used to control thefirst upstream channel and the second upstream channel, and multiplexesthe first upstream bandwidth grant and the second upstream bandwidthgrant, to provide the multiplexed upstream bandwidth grant for each ONUon the downstream channel. In this way, the ONU can separately controldata sending on the first upstream channel and the second upstreamchannel based on the received upstream bandwidth grant, to ensure thatthe upstream data sequentially reaches the OLT through the firstupstream channel and the second upstream channel, and avoid a conflictbetween the upstream data.

In a possible design, the first upstream channel is used to transmitupstream service data, and the second upstream channel is used totransmit a registration response packet;

the OLT generates the first upstream bandwidth grant including anupstream sending timeslot, and generates the second upstream bandwidthgrant including a registration timeslot; and

when the ONU is in a registered state, the ONU sends the upstreamservice data to the OLT on the first upstream channel based on theupstream sending timeslot in the first upstream bandwidth grant; or

when the ONU is in an unregistered state, the ONU sends a registrationresponse packet to the OLT on the second upstream channel based on theregistration timeslot in the second upstream bandwidth grant.

Different from the prior art in which the ONU sends the upstream servicedata and an upstream registration packet to the OLT on a same upstreamchannel, in this embodiment, based on a registration status of the ONU,when the ONU is in the registered state, the ONU sends the upstreamservice data to the OLT on the first upstream channel, to performservice communication with the OLT; and when the ONU is in theunregistered state, the ONU sends the registration response packet tothe OLT on the second upstream channel, to complete registration withthe OLT. In this way, while an unregistered ONU in the PON system isbeing registered, a registered ONU can still send upstream service datato the OLT, to avoid a delay caused by registration of the ONU in thePON system.

In a possible design, the first upstream channel is used to transmitfirst upstream service data, and the second upstream channel is used totransmit a registration response packet and second upstream servicedata;

the OLT generates the first upstream bandwidth grant including a firstupstream sending timeslot, and generates the second upstream bandwidthgrant including a second upstream sending timeslot and a registrationtimeslot; and

when the ONU is in a registered state, the ONU sends the first upstreamservice data to the OLT on the first upstream channel based on the firstupstream sending timeslot in the first upstream bandwidth grant, andsends the second upstream service data to the OLT on the second upstreamchannel based on the second upstream sending timeslot in the secondupstream bandwidth grant; or

when the ONU is in an unregistered state, the ONU sends a registrationresponse packet to the OLT on the second upstream channel based on theregistration timeslot in the second upstream bandwidth grant.

In this embodiment, the ONU sends upstream service data of a low-delayservice on the first upstream channel, and sends upstream service dataof a high-delay service and performs ONU registration on the secondupstream channel, thereby sending service data on two upstream channelsto improve a transmission rate of the upstream service data whilepreventing ONU registration from affecting the low-delay service.

In a possible design, the OLT obtains channel transmission quality ofthe first upstream channel and the second upstream channel; and when thechannel transmission quality of the first upstream channel is betterthan the channel transmission quality of the second upstream channel,the OLT controls the registration function to be disabled on the firstupstream channel and controls the registration function to be enabled onthe second upstream channel.

In this embodiment, the OLT flexibly configures enabling or disabling ofthe registration function on an upstream channel based on the channeltransmission quality of the first upstream channel and the secondupstream channel, to ensure that a low-delay service can be transmittedon an upstream channel with relatively desirable transmission quality,and further improve data transmission quality of the PON system.

In a possible design, the OLT stores the generated upstream bandwidthgrant; and

the OLT controls receiving of the upstream data based on the upstreambandwidth grant, and/or performs, based on the upstream bandwidth grant,authentication and parsing on the upstream data sent by each ONU.

In this embodiment, the OLT controls receiving of the upstream data byusing the generated upstream bandwidth grant, so that the upstream datais received more accurately. In addition, the OLT performsauthentication on the received upstream data by using the upstreambandwidth grant, to filter upstream data sent by an unauthorized ONU,thereby preventing an ONU that performs unauthorized access fromaffecting the PON system and further improving security of the PONsystem.

In a possible design, the ONU determines a service class of each servicebased on a delay requirement of the service; and

when the service class indicates that the service belongs to a firstclass, the ONU sends, on the first upstream channel, upstream datacorresponding to the service; or

when the service class indicates that the service belongs to a secondclass, the ONU sends, on the second upstream channel, upstream datacorresponding to the service, where

a delay requirement of a service belonging to the first class is higherthan a delay requirement of a service belonging to the second class.

In this embodiment, the ONU classifies services based on a service delayrequirement, selects the first upstream channel on which theregistration function is disabled, to send upstream data correspondingto a low-delay service, and selects the second upstream channel on whichthe registration function is enabled, to send upstream datacorresponding to a high-delay service, to ensure that the low-delayservice is not affected by ONU registration and satisfy a system delayrequirement of the low-delay service.

In a possible design, if the system is a GPON system, a BWmap messagecarries the upstream bandwidth grant; or

if the system is an EPON system, a Gate message carries the upstreambandwidth grant.

For different types of PON systems, the OLT adds the upstream bandwidthgrant to different types of messages, to implement upstream control overthe ONU by using the upstream bandwidth grant and improve applicabilityof the OLT.

In a possible design, when the BWmap message carries the upstreambandwidth grant, a predetermined bit of a predetermined field in theBWmap message is used to identify an upstream channel corresponding tothe BWmap message; and

when the Gate message carries the upstream bandwidth grant, a channelidentifier field newly added to the Gate message is used to identify anupstream channel corresponding to the Gate message, or operation code ofthe Gate message is used to identify an upstream channel correspondingto the Gate message, where

the predetermined field is a start time field or a grant size field, andthe predetermined bit is one most significant bit or two mostsignificant bits of the predetermined field.

In a possible design, the downstream channel, the first upstreamchannel, and the second upstream channel share the ODN in a wavelengthdivision multiplexing manner, and wavelengths of the first upstreamchannel and the second upstream channel are different.

In this embodiment, upstream and downstream channels in the PON systemseparately use different wavelengths, and share the ODN in a wavelengthdivision multiplexing manner, to avoid interference between upstream anddownstream channels and ensure normal transmission of upstream data anddownstream data.

According to a second aspect, an OLT is provided, where the OLTincludes: at least one dynamic bandwidth allocation (DBA) schedulingmodule, a downstream transmission convergence (TC) module, an upstreamTC module, a downstream transmitter, a first upstream burst receiver,and a second upstream burst receiver, where

the DBA scheduling module is configured to generate an upstreambandwidth grant, where the upstream bandwidth grant is used to controleach ONU to send upstream data:

the downstream TC module is connected to the DBA scheduling module, andis configured to generate, through downstream framing and convergence,downstream data including the upstream bandwidth grant;

the downstream transmitter is connected to the downstream TC module, andis configured to send the downstream data to each ONU on a downstreamchannel;

the upstream TC module is connected to the first upstream burstreceiver, and is configured to receive, by using the first upstreamburst receiver, the upstream data sent by each ONU on a first upstreamchannel; and

the upstream TC module is further connected to the second upstream burstreceiver, and is configured to receive, by using the second upstreamburst receiver, the upstream data sent by each ONU on a second upstreamchannel, where

a registration function is disabled on the first upstream channel, theregistration function is enabled on the second upstream channel, and theregistration function is used to register an unregistered ONU.

Different from the prior art in which the OLT receives upstream servicedata and performs ONU registration on one upstream channel, in thisembodiment, the OLT receives upstream service data and performs ONUregistration respectively on the first upstream channel on which theregistration function is disabled and the second upstream channel onwhich the registration function is enabled, to prevent ONU registrationfrom affecting sending of upstream data of a low-delay service whileensuring normal ONU registration, and satisfy a system delay requirementof the low-delay service.

In a possible design, the downstream data includes a first upstreambandwidth grant and a second upstream bandwidth grant, the firstupstream bandwidth grant is used to control the ONU to send upstreamdata on the first upstream channel, and the second upstream bandwidthgrant is used to control the ONU to send upstream data on the secondupstream channel.

In a possible design, the OLT includes a first DBA scheduling module, asecond DBA scheduling module, and a multiplexing module, where

the first DBA scheduling module is configured to generate the firstupstream bandwidth grant:

the second DBA scheduling module is configured to generate the secondupstream bandwidth grant;

the multiplexing module is connected to the first DBA scheduling moduleand the second DBA scheduling module, and is configured to multiplex thefirst upstream bandwidth grant and the second upstream bandwidth grant;and

the multiplexing module is further connected to the downstream TCmodule, and is configured to provide the multiplexed upstream bandwidthgrant for the downstream TC module.

In this embodiment, the OLT generates the first upstream bandwidth grantby using the first DBA scheduling module and generates the secondupstream bandwidth grant by using the second DBA scheduling module, andmultiplexes the first upstream bandwidth grant and the second upstreambandwidth grant by using the multiplexing module, to provide themultiplexed upstream bandwidth grant for each ONU on the downstreamchannel. In this way, the ONU can separately control sending of upstreamdata on the first upstream channel and the second upstream channel basedon the received upstream bandwidth grant, to ensure that the upstreamdata sequentially reaches the OLT through the first upstream channel andthe second upstream channel, and avoid a conflict between the upstreamdata.

In a possible design, the first upstream channel is used to transmitupstream service data, and the second upstream channel is used totransmit a registration response packet;

the first DBA scheduling module is configured to generate the firstupstream bandwidth grant including an upstream sending timeslot; and

the second DBA scheduling module is configured to generate the secondupstream bandwidth grant including a registration timeslot, where

the upstream sending timeslot is used to instruct the registered ONU tosend the upstream service data on the first upstream channel, and theregistration timeslot is used to instruct the unregistered ONU to sendthe registration response packet on the second upstream channel.

In this embodiment, the OLT controls, by using the first DBA schedulingmodule, the first upstream channel to be used only to transmit theupstream service data, and controls, by using the second DBA schedulingmodule, the second upstream channel to be used only to transmit theregistration response packet, so that while an unregistered ONU in a PONsystem sends the registration response packet on the second upstreamchannel, a registered ONU can still send the upstream service data onthe first upstream channel, to prevent ONU registration from affectingsending of the upstream service data.

In a possible design, the first upstream channel is used to transmitfirst upstream service data, and the second upstream channel is used totransmit a registration response packet and second upstream servicedata:

the first DBA scheduling module is configured to generate the firstupstream bandwidth grant including a first upstream sending timeslot;and

the second DBA scheduling module is configured to generate the secondupstream bandwidth grant including a second upstream sending timeslotand a registration timeslot, where

the first upstream sending timeslot is used to instruct the registeredONU to send the first upstream service data on the first upstreamchannel, the second upstream sending timeslot is used to instruct theregistered ONU to send the second upstream service data on the secondupstream channel, the registration timeslot is used to instruct theunregistered ONU to send the registration response packet on the secondupstream channel, and a delay requirement of the first upstream servicedata is higher than a delay requirement of the second upstream servicedata.

In this embodiment, the OLT controls, by using the first DBA schedulingmodule, the first upstream channel to be used only to transmit upstreamservice data corresponding to a low-delay service, and controls, byusing the second DBA scheduling module, the second upstream channel tobe used to transmit a registration response packet and upstream servicedata corresponding to a high-delay service, thereby sending upstreamservice data on two upstream channels to improve a transmission rate ofthe upstream service data while preventing ONU registration fromaffecting the low-delay service.

In a possible design, the OLT further includes a control module, and thecontrol module is connected to the first DBA scheduling module and thesecond DBA scheduling module; and

the control module is configured to: control the first DBA schedulingmodule to disable the registration function, and control the second DBAscheduling module to enable the registration function, where

the second upstream bandwidth grant generated by the second DBAscheduling module that enables the registration function includes theregistration timeslot, and the registration timeslot is used to instructthe unregistered ONU to send the registration response packet on thesecond upstream channel.

In this embodiment, the control module is disposed in the OLT, and thecontrol module is configured to control the first DBA scheduling moduleand the second DBA scheduling module to enable and disable theregistration function, to flexibly configure the first upstream channeland the second upstream channel.

In a possible design, the OLT includes one DBA scheduling module and acontrol module connected to the DBA scheduling module:

the control module is configured to control the DBA scheduling module toenable or disable the registration function;

when disabling the registration function, the DBA scheduling module isconfigured to: generate the first upstream bandwidth grant including afirst upstream sending timeslot, or generate the first upstreambandwidth grant including the first upstream sending timeslot and thesecond upstream bandwidth grant including a second upstream sendingtimeslot; and

when enabling the registration function, the DBA scheduling module isfurther configured to generate the first upstream bandwidth grantincluding the first upstream sending timeslot and the second upstreambandwidth grant including a registration timeslot, where

the first upstream sending timeslot is used to instruct the registeredONU to send upstream service data on the first upstream channel, thesecond upstream sending timeslot is used to instruct the registered ONUto send upstream service data on the second upstream channel, and theregistration timeslot is used to instruct the unregistered ONU to send aregistration response packet on the second upstream channel.

In this embodiment, the OLT controls, by using the control module, theDBA scheduling module to enable or disable the registration function,and the DBA scheduling module generates the corresponding first upstreambandwidth grant and the corresponding second upstream bandwidth grantbased on enabling and disabling states of the registration function, tosequentially manage the first upstream channel and the second upstreamchannel.

In a possible design, the OLT further includes a memory;

the memory is connected to each DBA scheduling module, and is configuredto store the upstream bandwidth grant generated by each DBA schedulingmodule; and

the upstream TC module is connected to the memory, and is configured to:control, based on the upstream bandwidth grant, the first upstream burstreceiver and the second upstream burst receiver to receive the upstreamdata, and/or perform, based on the upstream bandwidth grant,authentication and parsing on the upstream data sent by each ONU.

In this embodiment, the upstream TC module controls, by using thegenerated upstream bandwidth grant, each upstream burst receiver toreceive the upstream data, so that the upstream data is received moreaccurately. In addition, the upstream TC module performs authenticationon the received upstream data by using the upstream bandwidth grant, tofilter upstream data sent by an unauthorized ONU, thereby preventing anONU that performs unauthorized access from affecting the PON system andfurther improving security of the PON system.

In a possible design, if the OLT is used in a GPON system, a BWmapmessage carries the upstream bandwidth grant; or

if the OLT is used in an EPON system, a Gate message carries theupstream bandwidth grant.

In a possible design, when the BWmap message carries the upstreambandwidth grant, a predetermined bit of a predetermined field in theBWmap message is used to identify an upstream channel corresponding tothe BWmap message; and

when the Gate message carries the upstream bandwidth grant, a channelidentifier field newly added to the Gate message is used to identify anupstream channel corresponding to the Gate message, or operation code ofthe Gate message is used to identify an upstream channel correspondingto the Gate message, where the predetermined field is a start time fieldor a grant size field, and the predetermined bit is one most significantbit or two most significant bits of the predetermined field.

In a possible design, the downstream channel, the first upstreamchannel, and the second upstream channel share one optical distributionnetwork (ODN) in a wavelength division multiplexing manner, andwavelengths of the first upstream channel and the second upstreamchannel are different.

According to a third aspect, an ONU is provided. The ONU includes: adownstream TC module, at least one DBA response module, an upstream TCmodule, a downstream receiver, a first upstream burst transmitter, and asecond upstream burst transmitter;

the downstream TC module is connected to the downstream receiver and theDBA response module, and is configured to provide, for the DBA responsemodule, downstream data received by the downstream receiver on adownstream channel, where the downstream data is sent by an OLT;

the DBA response module is connected to the upstream TC module, and isconfigured to control, based on an upstream bandwidth grant included inthe downstream data, the upstream TC module to send upstream data:

the upstream TC module is connected to the first upstream bursttransmitter, and is configured to send the upstream data on a firstupstream channel by using the first upstream burst transmitter; and

the upstream TC module is connected to the second upstream bursttransmitter, and is configured to send the upstream data on a secondupstream channel by using the second upstream burst transmitter, where

a registration function is disabled on the first upstream channel, theregistration function is enabled on the second upstream channel, and theregistration function is used to register an unregistered ONU.

Different from the prior art in which the ONU sends upstream servicedata and performs ONU registration on one upstream channel, in thisembodiment, the ONU sends upstream service data and performs ONUregistration respectively on the first upstream channel on which theregistration function is disabled and the second upstream channel onwhich the registration function is enabled, to prevent ONU registrationfrom affecting sending of upstream service data, and satisfy a systemdelay requirement of a low-delay service.

In a possible design, the downstream data includes a first upstreambandwidth grant and a second upstream bandwidth grant, the firstupstream bandwidth grant is used to control the ONU to send upstreamdata on the first upstream channel and the second upstream bandwidthgrant is used to control the ONU to send upstream data on the secondupstream channel.

In a possible design, the ONU includes a first DBA response module, asecond DBA response module, and a demultiplexing module, where

the demultiplexing module is connected to the downstream TC module, andis configured to demultiplex the upstream bandwidth grant received bythe downstream TC module, to obtain the first upstream bandwidth grantand the second upstream bandwidth grant;

the first DBA response module is connected to the demultiplexing module,and is configured to control, based on the first upstream bandwidthgrant, the upstream TC module to send the upstream data on the firstupstream channel; and

the second DBA response module is connected to the demultiplexingmodule, and is configured to control, based on the second upstreambandwidth grant, the upstream TC module to send the upstream data on thesecond upstream channel.

In this embodiment, after receiving the downstream data, the ONUdemultiplexes the upstream bandwidth grant in the downstream data byusing the demultiplexing module, to obtain the first upstream bandwidthgrant and the second upstream bandwidth grant, and separately sends theupstream data based on the first upstream bandwidth grant and the secondupstream bandwidth grant, to ensure that the upstream data sequentiallyreaches the OLT and avoid a conflict between the upstream data.

In a possible design, the first upstream channel is used to transmitupstream service data, and the second upstream channel is used totransmit a registration response packet;

if the ONU is in a registered state, the upstream TC module isconfigured to send a first enabling signal to the first upstream bursttransmitter based on an upstream sending timeslot in the first upstreambandwidth grant, where the first enabling signal is used to instruct thefirst upstream burst transmitter to send the upstream service data onthe first upstream channel; and

if the ONU is in an unregistered state, the upstream TC module isconfigured to send a second enabling signal to the second upstream bursttransmitter based on a registration timeslot in the second upstreambandwidth grant, where the second enabling signal is used to instructthe second upstream burst transmitter to send the registration responsepacket on the second upstream channel.

In this embodiment, the first upstream channel is configured to be usedonly to transmit the upstream service data, and the second upstreamchannel is configured to be used only to transmit the registrationresponse packet, so that while an unregistered ONU in the PON systemsends the registration response packet on the second upstream channel, aregistered ONU can send the upstream service data on the first upstreamchannel, to prevent a registration data packet from affecting sending ofthe upstream service data.

In a possible design, the ONU includes an optical module slot, and theoptical module slot is used for a first optical module or a secondoptical module to slot into;

the first optical module includes at least the downstream receiver andthe first upstream burst transmitter; and

the second optical module includes at least the downstream receiver andthe second upstream burst transmitter, where

when the ONU is in the unregistered state, the second optical module isslot into the optical module slot; or when the ONU is in the registeredstate, the first optical module is slot into the optical module slot.

In this embodiment, the downstream receiver and the first upstream bursttransmitter are integrated into the first optical module, and thedownstream receiver and the second upstream burst transmitter areintegrated into the second optical module, so that different newly addedONUs all can complete ONU registration by using the same second opticalmodule, thereby improving utilization of the second upstream bursttransmitter and reducing ONU manufacturing costs.

In a possible design, the first upstream channel is used to transmitfirst upstream service data, the second upstream channel is used totransmit a registration response packet and second upstream servicedata, and a delay requirement of the first upstream service data ishigher than a delay requirement of the second upstream service data;

if the ONU is in a registered state, the upstream TC module isconfigured to: send a third enabling signal to the first upstream bursttransmitter based on a first upstream sending timeslot in the firstupstream bandwidth grant, where the third enabling signal is used toinstruct the first upstream burst transmitter to send the first upstreamservice data on the first upstream channel; and send a fourth enablingsignal to the second upstream burst transmitter based on a secondupstream sending timeslot in the second upstream bandwidth grant, wherethe fourth enabling signal is used to instruct the second upstream bursttransmitter to send the second upstream service data on the secondupstream channel; and

if the ONU is in an unregistered state, the upstream TC module isconfigured to send a fifth enabling signal to the second upstream bursttransmitter based on a registration timeslot in the second upstreambandwidth grant, where the fifth enabling signal is used to instruct thesecond upstream burst transmitter to send the registration responsepacket on the second upstream channel.

In this embodiment, the first upstream channel is configured to be usedonly to transmit the first upstream service data, and the secondupstream channel is configured to transmit the registration responsepacket and the second upstream service data, to transmit the upstreamservice data on two upstream channels to improve a transmission rate ofthe upstream service data in the PON system while ensuring that ONUregistration does not affect sending of the first upstream service data.

In a possible design, the ONU further includes a service classificationmodule;

the service classification module is configured to: collect a delayrequirement of each service and determine a service class of the servicebased on the delay requirement;

the DBA response module is connected to the service classificationmodule, and is configured to: when the service class indicates that theservice belongs to a first class, control the upstream TC module tosend, on the first upstream channel, the first upstream service datacorresponding to the service; and

the DBA response module is further configured to: when the service classindicates that the service belongs to a second class, control theupstream TC module to send, on the second upstream channel, the secondupstream service data corresponding to the service.

In this embodiment, the ONU classifies services by using the serviceclassification module, selects the first upstream channel on which theregistration function is disabled, to send upstream data correspondingto a low-delay service, and selects the second upstream channel on whichthe registration function is enabled, to send upstream datacorresponding to a high-delay service, to ensure that the low-delayservice is not affected by ONU registration and satisfy a system delayrequirement of the low-delay service.

In a possible design, the ONU includes a first optical module slot and asecond optical module slot, the first optical module slot is used forthe first optical module to slot into, and the second optical moduleslot is used for the second optical module to slot into;

the first optical module includes at least the first upstream bursttransmitter; and

the second optical module includes at least the downstream receiver andthe second upstream burst transmitter, where

when the second upstream service data is transmitted, the second opticalmodule is slot into the second optical module slot; and when the firstupstream service data and the second upstream service data aretransmitted, the second optical module is slot into the second opticalmodule slot and the first optical module is slot into the first opticalmodule slot.

In a possible design, the ONU includes one DBA response module and achannel selection module;

the channel selection module is connected to the first upstream bursttransmitter, the second upstream burst transmitter, and the upstream TCmodule;

the DBA response module is configured to: control, based on the firstupstream bandwidth grant, the upstream TC module to send upstreamservice data, or control, based on the second upstream bandwidth grant,the upstream TC module to send a registration response packet; and

the channel selection module is configured to: when the ONU is in aregistered state, select the first upstream burst transmitter to sendthe upstream service data generated by the upstream TC module, or whenthe ONU is in an unregistered state, select the second upstream bursttransmitter to send the registration response packet generated by theupstream TC module.

In this embodiment, the channel selection module of the ONU sends theupstream service data on the first upstream channel, or sends theregistration response packet on the second upstream channel based on aregistration status of the ONU, to dynamically perform energyconservation of the ONU.

In a possible design, if the ONU is used in a GPON system, a BWmapmessage carries the upstream bandwidth grant; or

if the ONU is used in an EPON system, a Gate message carries theupstream bandwidth grant.

In a possible design, when the BWmap message carries the upstreambandwidth grant, a predetermined bit of a predetermined field in theBWmap message is used to identify an upstream channel corresponding tothe BWmap message; and

when the Gate message carries the upstream bandwidth grant, a channelidentifier field newly added to the Gate message is used to identify anupstream channel corresponding to the Gate message, or operation code ofthe Gate message is used to identify an upstream channel correspondingto the Gate message, where

the predetermined field is a start time field or a grant size field, andthe predetermined bit is one most significant bit or two mostsignificant bits of the predetermined field.

In a possible design, the downstream channel, the first upstreamchannel, and the second upstream channel share one ODN in a wavelengthdivision multiplexing manner, and wavelengths of the first upstreamchannel and the second upstream channel are different.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an architectural system diagram of a PON system according toan embodiment of this application;

FIG. 2 is a schematic structural diagram of an OLT according to a firstembodiment of this application;

FIG. 3 is a schematic structural diagram of an OLT according to a secondembodiment of this application;

FIG. 4 is a schematic structural diagram of an OLT according to a thirdembodiment of this application;

FIG. 5 is a schematic structural diagram of an ONU according to a firstembodiment of this application;

FIG. 6 is a schematic structural diagram of an ONU according to a secondembodiment of this application;

FIG. 7 is a schematic structural diagram of an ONU according to a thirdembodiment of this application;

FIG. 8 is a schematic structural diagram of an ONU according to a fourthembodiment of this application;

FIG. 9 is a schematic structural diagram of an ONU according to a fifthembodiment of this application:

FIG. 10 is a schematic structural diagram of an ONU according to a sixthembodiment of this application:

FIG. 11 is a flowchart of a data exchange process in a PON systemaccording to an embodiment of this application; and

FIG. 12 is a flowchart of a data exchange process in a PON systemaccording to another embodiment of this application.

DESCRIPTION OF EMBODIMENTS

To make the objectives, technical solutions, and advantages of thisapplication clearer, the following further describes the implementationsof this application in detail with reference to the accompanyingdrawings.

In this specification, “a plurality of” means two or more than two. Theterm “and/or” describes an association relationship for describingassociated objects and represents that three relationships may exist.For example, A and/or B may represent the following three cases; Only Aexists, both A and B exist, and only B exists. The character “/” usuallyindicates an “or” relationship between the associated objects.

In the prior art, a PON system includes only one downstream channel andone upstream channel. An OLT sends downstream data to a registered ONUon the downstream channel in a time division multiplexing manner.Correspondingly, each registered ONU sends upstream service data to theOLT on the upstream channel in an upstream sending timeslot of the ONUin a Time Division Multiple Access manner, to avoid a conflict betweenthe upstream service data. However, because a newly added ONU in the PONsystem also needs to be registered with the OLT on the upstream channel,during registration of the newly added ONU (usually 200 μs to 250 μs),each registered ONU needs to stop sending upstream service data on theupstream channel, to prevent a registration response packet sent by thenewly added ONU from conflicting with the upstream service data sent bythe registered ONU. Although a conflict between the upstream servicedata and the registration response packet can be effectively avoided byusing the foregoing conflict prevention mechanism, a delay of theupstream service data is increased. As a result, the existing PON systemcannot satisfy a delay requirement of a low-delay service such as ahigh-definition video (4K or 8K video) service, an augmented reality(AR) service, a virtual reality (VR) service, or a mobile fronthaulservice.

In the embodiments of this application, the PON system includes onedownstream channel and two upstream channels, a registration function isenabled on one of the two upstream channels, and the registrationfunction is disabled on the other. In the PON system, while anunregistered ONU performs registration and activation on the upstreamchannel on which the registration function is enabled, a registered ONUmay send upstream service data on the upstream channel on which theregistration function is disabled. In other words, the OLT cansimultaneously receive the upstream service data and a registrationresponse packet sent by the ONUs, to prevent ONU registration andactivation from affecting sending of the upstream service data.

FIG. 1 is an architectural system diagram of a PON system according toan embodiment of this application. The PON system includes an OLT 110and at least one ONU 120, and the OLT 110 is connected to each ONU 120by using an ODN 130.

The OLT 110 is a central office device in the PON system, and hasfunctions such as ONU registration, bandwidth allocation, and downstreamdata sending.

In this embodiment of this application, a downstream transmitter, afirst upstream burst receiver, and a second upstream burst receiver aredisposed in the OLT 110. The OLT 110 sends downstream data to the ONU120 by using the downstream transmitter (a downstream channel in the ODN130), and receives, by using the first upstream burst receiver and thesecond upstream burst receiver, upstream data sent by the ONU 120 inbursts.

The ODN 130 is used to provide an optical transmission channel betweenthe OLT 110 and each ONU 120. Specifically, the ODN 130 includes anoptical fiber 131 and a power splitter 132.

In this embodiment of this application, the PON system includes adownstream channel, a first upstream channel, and a second upstreamchannel, and the downstream channel, the first upstream channel, and thesecond upstream channel are used as logical channels in the ODN 130, andshare the ODN 130 in a wavelength division multiplexing manner. Inaddition, to prevent channels from affecting each other, a wavelength ofthe downstream channel is λ₁, a wavelength of the first upstream channelis λ₂, and a wavelength of the second upstream channel is λ₃, whereλ₂≠λ₃.

The ONU 120 is a user end device in the PON system, and has functionssuch as registration responding, bandwidth allocation requesting, anddownstream data receiving.

In this embodiment of this application, a downstream receiver, a firstupstream burst transmitter, and a second upstream burst transmitter aredisposed in each ONU 120. The ONU 120 receives, on the downstreamchannel by using the downstream receiver, downstream data sent by theOLT 110, sends upstream data on the first upstream channel in bursts byusing the first upstream burst transmitter, and sends upstream data onthe second upstream channel in bursts by using the second upstream bursttransmitter.

It should be noted that the PON system shown in FIG. 1 may be an EPONsystem or a GPON system. This is not limited in this embodiment of thisapplication.

FIG. 2 is a schematic structural diagram of an OLT according to anembodiment of this application. In this embodiment, an example in whichthe OLT is used in the PON system shown in FIG. 1 is used fordescription. The OLT includes: at least one DBA scheduling module 210, adownstream TC module 220, an upstream TC module 230, a downstreamtransmitter 240, a first upstream burst receiver 251, and a secondupstream burst receiver 252.

The DBA scheduling module 210 has a scheduling control function, and isconfigured to: generate an upstream bandwidth grant and control, byusing the upstream bandwidth grant, each ONU to send upstream data on afirst upstream channel and a second upstream channel. Specifically, afirst upstream bandwidth grant generated by the DBA scheduling module210 is used to control the ONU to send the upstream data on the firstupstream channel, and a second upstream bandwidth grant generated by theDBA scheduling module 210 is used to control the ONU to send theupstream data on the second upstream channel.

It should be noted that in different PON systems, messages used to carrythe upstream bandwidth grant generated by the DBA scheduling module 210are also different. Optionally, when the OLT is used in a GPON system, aBWmap message is used to carry the upstream bandwidth grant; or when theOLT is used in an EPON system, a Gate message is used to carry theupstream bandwidth grant. In this embodiment of this application, aspecific type of a message carrying the upstream bandwidth grant is notlimited.

The downstream TC module 220 is connected to each DBA scheduling module210, and is configured to: obtain the upstream bandwidth grant generatedby each DBA scheduling module 210, and generate, through downstreamframing and convergence, downstream data including the upstreambandwidth grant. The downstream data further includes downstream servicedata that the ONU requests to obtain, for example, video data and voicedata that the ONU requests to obtain.

Optionally, after completing upper-layer service adaptation, GPONencapsulation mode (GEM) encapsulation, TC framing, and physical layeradaptation, the downstream TC module 220 generates the downstream data.Upper-layer service adaptation includes user data adaptation, opticalnetwork unit management and control interface (OMCI) adaptation, and thelike.

Optionally, both the upstream bandwidth grants corresponding to thefirst upstream channel and the second upstream channel are sent to theONU on a same downstream channel. Correspondingly, after receiving theupstream bandwidth grant, the ONU needs to further determine an upstreamchannel corresponding to the upstream bandwidth grant, to send upstreamdata on the corresponding upstream channel based on the identifiedupstream bandwidth grant. Therefore, the upstream bandwidth grantincludes an upstream channel identifier, so that the ONU can identifythe received upstream bandwidth grant based on the upstream channelidentifier.

The downstream transmitter 240 is connected to the downstream TC module220, and is configured to send the downstream data generated by thedownstream TC module 220 to each ONU on a downstream channel.

The downstream transmitter 240 sends the downstream data to each ONU inthe PON system in a broadcast manner, and the downstream data istransmitted on the downstream channel in a form of an optical carriersignal.

The OLT may complete sending of the downstream data by using the DBAscheduling module 210, the downstream TC module 220, and the downstreamtransmitter 240. The ONU receiving the downstream data transmitsupstream data on the first upstream channel or the second upstreamchannel based on the upstream bandwidth grant included in the downstreamdata.

In a possible design, that the ONU sends the upstream data on theupstream channel includes the following cases:

1: when the ONU is unregistered, sending a registration response packeton the second upstream channel;

2: when the ONU is registered, sending upstream service data (upstreamservice data of a low-delay service and upstream service data of ahigh-delay service are all sent on the first upstream channel) on thefirst upstream channel;

3: when the ONU is registered and the system includes no unregisteredONU, sending upstream service data of a low-delay service on the firstupstream channel and sending upstream service data of a high-delayservice on the second upstream channel; and

4: when the ONU is registered and the system includes an unregisteredONU, sending upstream service data of a low-delay service only on thefirst upstream channel.

As shown in FIG. 2, the upstream TC module 230 of the OLT is connectedto the first upstream burst receiver 251 and the second upstream burstreceiver 252, so that the first upstream burst receiver 251 is used toreceive upstream data transmitted by the ONU on the first upstreamchannel, and the second upstream burst receiver 252 is used to receiveupstream data transmitted by the ONU on the second upstream channel. Theupstream data is transmitted on the first upstream channel and thesecond upstream channel in a form of an optical carrier signal.

In this embodiment of this application, a registration function isdisabled on the first upstream channel, the registration function isenabled on the second upstream channel, and enabling and disabling ofthe registration function on the first upstream channel and the secondupstream channel are controlled by the DBA scheduling module 210.

When the registration function is disabled on the first upstreamchannel, and the registration function is enabled on the second upstreamchannel, an unregistered ONU in the PON system sends a registrationresponse packet only on the second upstream channel. Correspondingly,the OLT can receive the registration response packet on the secondupstream channel only by using the second upstream burst receiver 262,and register the unregistered ONU based on the registration responsepacket.

Obviously, while an unregistered ONU in the PON system sends theregistration response packet to the OLT on the second upstream channel,a registered ONU in the system can still send upstream service data tothe OLT on the first upstream channel, and the upstream service data andthe registration response packet on the different upstream channels donot conflict with each other.

It is easily understood that the ONU may transmit, on the first upstreamchannel, upstream service data corresponding to a low-delay service (aservice having a relatively high delay requirement), and transmit, onthe second upstream channel, a registration response packet and/orupstream service data corresponding to a high-delay service (a servicehaving a relatively low delay requirement), to ensure that the systemsatisfies the delay requirement of the low-delay service while ensuringnormal registration of the unregistered ONU.

It should be noted that because the downstream channel, the firstupstream channel, and the second upstream channel share one ODN in awavelength division multiplexing manner, and wavelengths of the firstupstream channel and the second upstream channel are different, awavelength multiplexer/demultiplexer 260 is further disposed in the OLT,and is configured to combine or split an optical carrier signal on theupstream and downstream channels.

In a possible implementation, two DBA scheduling modules are disposed inthe OLT, and the OLT separately controls sending of upstream data on thefirst upstream channel and the second upstream channel by using the twoDBA scheduling modules. Based on the OLT shown in FIG. 2, as shown inFIG. 3, the OLT includes a first DBA scheduling module 211, a second DBAscheduling module 212, and a multiplexing module 270.

The first DBA scheduling module 211 is configured to generate the firstupstream bandwidth grant, and the first upstream bandwidth grant is usedto control sending of upstream data on the first upstream channel. Thesecond DBA scheduling module 212 is configured to generate the secondupstream bandwidth grant, and the second upstream bandwidth grant isused to control sending of upstream data on the second upstream channel.

Optionally, to implement load balancing of the first upstream channeland the second upstream channel, the first DBA scheduling module 211 isconnected to the second DBA scheduling module 212. When the upstreambandwidth grant is generated, the first DBA scheduling module 211 andthe second DBA scheduling module 212 exchange information through theconnection, to implement upstream bandwidth scheduling optimization.This is not limited in this embodiment of this application.

The multiplexing module 270 is connected to the first DBA schedulingmodule 211 and the second scheduling module 212, and is configured to:obtain the first upstream bandwidth grant and the second upstreambandwidth grant and multiplex the upstream bandwidth grants, to finallygenerate the multiplexed upstream bandwidth grant.

Because the first upstream bandwidth grant and the second upstreambandwidth grant are sent to the ONU on the same downstream channel afterbeing multiplexed, after obtaining the first upstream bandwidth grantand the second upstream bandwidth grant, the multiplexing module 270needs to add corresponding upstream channel identifiers to the upstreambandwidth grants, and then multiplexes the upstream bandwidth grants towhich the upstream channel identifiers are added. In this way, the ONUcan identify the first upstream bandwidth grant and the second upstreambandwidth grant, and determine upstream channels corresponding todifferent upstream bandwidth grants. Optionally, the upstream channelidentifier may alternatively be generated by the DBA scheduling module,that is, the DBA scheduling module directly generates the upstreambandwidth grant carrying the upstream channel identifier. This is notlimited in this embodiment of this application.

In a possible implementation, when the OLT is used in a GPON system, themultiplexing module 270 separately adds an upstream channel identifierto a first BWmap message (generated by the first DBA scheduling module)and a second BWmap message (generated by the second DBA schedulingmodule).

Specifically, because a start time field and a grant size field in theBWmap message are both 16-bit, but an actual value range is from 0 to9719 (including 0 and 9719), that is, only 14 bits are used, themultiplexing module 270 may identify, by using one most significant bitor two most significant bits of the start time field and the grant sizefield, an upstream channel corresponding to the BWmap message. Forexample, when the one most significant bit is 0, it indicates that theBWmap message corresponds to the first upstream channel, and when theone most significant bit is 1, it indicates that the BWmap messagecorresponds to the second upstream channel. Alternatively, when the twomost significant bits are 00, it indicates that the BWmap messagecorresponds to the first upstream channel, and when the two mostsignificant bits are 11, it indicates that the BWmap message correspondsto the second upstream channel.

In another possible implementation, when the OLT is used in an EPONsystem, the multiplexing module (or the DBA scheduling module) newlyadds a channel identifier field to a Gate message to indicate anupstream channel corresponding to the Gate message. For example, achannel identifier field CH_Num is newly added to the Gate message, whenCH_Num is 0x00, it indicates that the Gate message corresponds to thefirst upstream channel, and when CH_Num is 0x01, it indicates that theGate message corresponds to the second upstream channel.

Optionally, when the OLT is used in the EPON system, the upstreamchannel corresponding to the Gate message may alternatively beidentified by using different operation codes (Opcode). For example,when operation code of the Gate message is 0xaa, it indicates that theGate message corresponds to the first upstream channel, and when theoperation code of the Gate message is 0xbb, it indicates that the Gatemessage corresponds to the second upstream channel.

After the upstream channel identifiers are added to the first upstreambandwidth grant and the second upstream bandwidth grant, themultiplexing module 270 converges and multiplexes the first upstreambandwidth grant and the second upstream bandwidth grant, to obtain themultiplexed upstream bandwidth grant.

The multiplexing module 270 is further connected to the downstream TCmodule 220, and is configured to provide the multiplexed upstreambandwidth grant for the downstream TC module 220. The downstream TCmodule 220 sends, on the downstream channel by using the downstreamtransmitter 240, the downstream data including the upstream bandwidthgrant.

Optionally, the multiplexing module 270 is further connected to theupstream TC module 230, and is configured to provide the multiplexedupstream bandwidth grant for the upstream TC module 230.Correspondingly, based on the upstream bandwidth grant, the upstream TCmodule 230 controls the first upstream burst receiver 251 to receive theupstream data transmitted by the ONU on the first upstream channel, andcontrols the second upstream burst receiver 252 to receive the upstreamdata transmitted by the ONU on the second upstream channel.

The upstream data is sent on the first upstream channel and the secondupstream channel in bursts. Therefore, optionally, as shown in FIG. 3,the OLT further includes a memory 280, so that the OLT learns of anarriving time of the upstream data, and the upstream burst receiver ofthe OLT makes preparations for receiving data before the upstream dataarrives. The memory 280 is connected to each DBA scheduling module, andthe memory 280 is further connected to the multiplexing module 270 andthe upstream TC module 230.

After obtaining the upstream bandwidth grant generated by each DBAscheduling module, the memory 280 makes two copies of the upstreambandwidth grant. One copy is sent to the multiplexing module 270. Themultiplexing module 270 multiplexes the upstream bandwidth grants, andthen transmits the multiplexed upstream bandwidth grant to thedownstream TC module 220. The downstream TC module 220 generates,through downstream framing and convergence, the downstream dataincluding the upstream bandwidth grant, and finally sends the downstreamdata to the ONU. The other copy is stored and sent to the upstream TCmodule 230. Based on the upstream bandwidth grant, the upstream TCmodule 230 controls the first upstream burst receiver 251 to receive theupstream data sent by the ONU in bursts on the first upstream channel,and controls the second upstream burst receiver 252 to receive theupstream data sent by the ONU in bursts on the second upstream channel.

Optionally, after obtaining the upstream bandwidth grant, before theupstream data arrives, the upstream TC module 230 separately resets thefirst upstream burst receiver 251 and the second upstream burst receiver252, to instruct the first upstream burst receiver 251 to start toreceive the upstream data transmitted by the ONU on the first upstreamchannel, and instruct the second upstream burst receiver 252 to start toreceive the upstream data transmitted by the ONU on the second upstreamchannel.

Further, the upstream TC module 230 may further identify, based on theupstream bandwidth grant, an ONU that transmits upstream data on thefirst upstream channel and an ONU that transmits upstream data on thesecond upstream channel, to further forward the upstream data.

Further, the upstream TC module 230 may further perform, based on theupstream bandwidth grant, authentication on the upstream data sent bythe ONU, to determine whether the PON system has an ONU that performsunauthorized access. For example, if detecting upstream data outside anupstream sending timeslot indicated by the upstream bandwidth grant, theupstream TC module 230 determines that the PON system has an ONU thatperforms unauthorized access. For another example, after receivingupstream data, the upstream TC module 230 searches the upstreambandwidth grant for a corresponding ONU identifier based on an upstreamsending timeslot in which a sending party (an ONU sending the upstreamdata) sends the upstream data, and if a found ONU identifier isinconsistent with an ONU identifier of the sending party, determinesthat the PON system has an ONU that performs unauthorized access. TheONU identifier is an LLID or an ONU ID allocated by the OLT. Forupstream data that fails to be authenticated, the OLT directly filtersthe upstream data, and for upstream data that has been authenticated,the OLT further parses the upstream data to obtain service informationincluded in the upstream data.

In another possible implementation, the multiplexing module 270 may befurther connected to the first DBA scheduling module 211 and the secondDBA scheduling module 212, and provide the multiplexed upstreambandwidth grant for the memory 280 connected to the multiplexing module270. The memory 280 separately provides the multiplexed upstreambandwidth grant for the downstream TC module 220 and the upstream TCmodule 230 connected to the memory 280. A connection sequence of themultiplexing module and the memory is not limited in this embodiment ofthis application.

In this embodiment, the memory is used to provide the upstream bandwidthgrant for the upstream TC module, so that the upstream TC module cancontrol, based on the upstream bandwidth grant, the upstream burstreceiver to receive the upstream data. Therefore, the upstream data isreceived more accurately. In addition, the upstream TC module mayfurther perform authentication on the received upstream data by usingthe upstream bandwidth grant, to prevent an ONU that performsunauthorized access from affecting the PON system.

In the OLT shown in FIG. 3, when the first DBA scheduling module 211 isconfigured to disable the registration function, and the second DBAscheduling module 212 is configured to enable the registration function,a newly added ONU can be registered only on the second upstream channelcorresponding to the second DBA scheduling module 212. To flexiblyconfigure the registration function, as shown in FIG. 3, the OLT furtherincludes a control module 290.

The control module 290 is connected to the first DBA scheduling module211 and the second DBA scheduling module 212, and is configured tocontrol one of the first DBA scheduling module 211 and the second DBAscheduling module 212 to enable the registration function, to controlenabling and disabling of the registration function on a correspondingupstream channel.

Optionally, according to a received configuration command, the controlmodule 290 configures enabling and disabling of the registrationfunction by the first DBA scheduling module 211 and the second DBAscheduling module 212. The configuration command is inputted by anexternal device connected to the OLT.

Optionally, the control module 290 obtains channel transmission qualityof the first upstream channel and the second upstream channel atpredetermined intervals, when the channel transmission quality of thefirst upstream channel is better than the channel transmission qualityof the second upstream channel, controls the first DBA scheduling module211 to disable the registration function and controls the second DBAscheduling module 212 to enable the registration function: and when thechannel transmission quality of the second upstream channel is betterthan the channel transmission quality of the first upstream channel,controls the first DBA scheduling module 211 to enable the registrationfunction and controls the second DBA scheduling module 212 to disablethe registration function. In this embodiment of this application, onlyan example in which the control module 290 controls the first DBAscheduling module 211 to disable the registration function and controlsthe second DBA scheduling module 212 to enable the registration functionis used for description, and constitutes no limitation on thisapplication.

The first upstream bandwidth grant generated by the first DBA schedulingmodule that disables the registration function includes an upstreamsending timeslot, and a registered ONU in the PON system sends upstreamservice data on the first upstream channel based on the upstream sendingtimeslot. The second upstream bandwidth grant generated by the secondDBA scheduling module that enables the registration function includes aregistration timeslot, and an unregistered ONU in the PON system sends aregistration response packet on the second upstream channel based on theregistration timeslot. Finally, the OLT completes registration andactivation for the unregistered ONU based on the registration responsepacket.

Optionally, in the OLT shown in FIG. 3, the first upstream channel isconfigured to transmit only upstream service data, and the secondupstream channel is configured to transmit only a registration responsepacket. To be specific, all upstream service data in the PON system istransmitted on the first upstream channel, and all registration responsepackets in the system are transmitted on the second upstream channel.

The first DBA scheduling module 211 is configured to generate the firstupstream bandwidth grant including an upstream sending timeslot.

The upstream sending timeslot is used to instruct a registered ONU inthe PON system to send upstream service data on the first upstreamchannel, and upstream sending timeslots corresponding to different ONUsare different. For a manner of specifying the upstream sending timeslot,refer to the GPON family of standards and/or the EPON family ofstandards. This is not limited in this embodiment of this application.

Optionally, the first upstream bandwidth grant includes a correspondencebetween an ONU identifier and an upstream sending timeslot. The ONUsearches for a corresponding upstream sending timeslot based on an ONUidentifier of the ONU, and sends upstream service data in bursts in atime period indicated by the upstream sending timeslot.

The second DBA scheduling module 212 is configured to generate thesecond upstream bandwidth grant including a registration timeslot.

The registration timeslot is used to instruct an unregistered ONU in thePON system to send a registration response packet on the second upstreamchannel. The unregistered ONU receives the second upstream bandwidthgrant on the downstream channel, and when detecting that the secondupstream bandwidth grant includes the registration timeslot, sends theregistration response packet in a time period indicated by theregistration timeslot.

Obviously, in a registration period (that is, a quiet zone), theunregistered ONU sends the registration response packet on the secondupstream channel, and the registered ONU sends the upstream service dataon the first upstream channel. Therefore, there is no conflict betweenthe registration response packet and the upstream service data. In anon-registration period, the registered ONU sends the upstream servicedata on the first upstream channel, and the second upstream channel isin a disabled state. In this case, the second upstream burst receiver ofthe OLT and a second upstream burst transmitter of the ONU both stopworking, to dynamically perform energy conservation of the PON system.

Optionally, in the OLT shown in FIG. 3, the first upstream channel isconfigured to transmit only first upstream service data, and the secondupstream channel is configured to transmit a registration responsepacket and second upstream service data.

The first DBA scheduling module 211 is configured to generate the firstupstream bandwidth grant including a first upstream sending timeslot.

The second DBA scheduling module 212 is configured to generate thesecond upstream bandwidth grant including a second upstream sendingtimeslot and a registration timeslot.

The first upstream sending timeslot is used to instruct a registered ONUto send the first upstream service data on the first upstream channel,the second upstream sending timeslot is used to instruct the registeredONU to send the second upstream service data on the second upstreamchannel, the registration timeslot is used to instruct an unregisteredONU to send the registration response packet on the second upstreamchannel, and a delay requirement of the first upstream service data ishigher than a delay requirement of the second upstream service data.

Optionally, a delay of the first upstream service data is less than thatof the second upstream service data. To be specific, the ONU sends, onthe first upstream channel, upstream service data corresponding to alow-delay service, and registers a newly added ONU and sends, on thesecond upstream channel, upstream service data corresponding to ahigh-delay service.

It should be noted that when the unregistered ONU sends the registrationresponse packet based on the registration timeslot in the secondupstream bandwidth grant, the registered ONU needs to stop sending thesecond upstream service data on the second upstream channel, to preventthe second upstream service data from conflicting with the registrationresponse packet on the second upstream channel.

Obviously, in this embodiment, the PON system can send the upstreamservice data on the two upstream channels while ensuring that thelow-delay service is not affected by an ONU registration process,thereby increasing a transmission rate of the upstream service data inthe entire PON system.

In the foregoing embodiment, an example in which two DBA schedulingmodules are disposed in the OLT is used for description. In anotherpossible implementation, only one DBA scheduling module may be disposedin the OLT, and the OLT controls sending of the upstream data on thefirst upstream channel and the second upstream channel by using the DBAscheduling modules. Based on the OLT shown in FIG. 2, as shown in FIG.4, the OLT includes a DBA scheduling module 210 and a control module290.

The control module 290 is connected to the DBA scheduling module 210,and is configured to control the DBA scheduling module 210 to enable ordisable a registration function.

Optionally, the control module 290 controls, at predetermined intervals,the DBA scheduling module 210 to enable the registration function, andwhen duration of enabling the registration function reaches presetduration, controls the DBA scheduling module 210 to disable theregistration function.

When enabling the registration function, the DBA scheduling module 210generates a first upstream bandwidth grant including a first upstreamsending timeslot and a second upstream bandwidth grant including aregistration timeslot.

Correspondingly, after each ONU in the PON system receives the firstupstream bandwidth grant and the second upstream bandwidth grant, aregistered ONU sends first upstream service data on the first upstreamchannel based on the first upstream sending timeslot included in thefirst upstream bandwidth grant; and an unregistered ONU sends aregistration response packet and completes registration and activationon the second upstream channel based on the registration timeslotincluded in the second upstream bandwidth grant.

When the registration function is disabled and the second upstreamchannel is configured to transmit only the registration response packet,the DBA scheduling module 210 generates the first upstream bandwidthgrant including the first upstream sending timeslot, to instruct aregistered ONU in the system to send upstream service data on the firstupstream channel.

When the registration function is disabled, and the second upstreamchannel is configured to transmit the registration response packet andsecond upstream service data, the DBA scheduling module 210 generatesthe first upstream bandwidth grant including the first upstream sendingtimeslot and the second upstream bandwidth grant including a secondupstream sending timeslot, to instruct the registered ONU in the systemto send the first upstream service data on the first upstream channeland send the second upstream service data on the second upstreamchannel.

Upstream data is sent on the first upstream channel and the secondupstream channel in bursts. Therefore, optionally, as shown in FIG. 4,the OLT further includes a memory 280, so that the OLT learns of anarriving time of the upstream data, and the upstream burst receiver ofthe OLT makes preparations for receiving data before the upstream dataarrives. The memory 280 is connected to the DBA scheduling module 210,and the memory 280 is further connected to the downstream TC module 220and the upstream TC module 230.

After obtaining the upstream bandwidth grant generated by the DBAscheduling module 210, the memory 280 makes two copies of the upstreambandwidth grant. One copy is sent to the downstream TC module 220. Thedownstream TC module 220 generates, through downstream framing andconvergence, downstream data including the upstream bandwidth grant, andfinally sends the downstream data to the ONU. The other copy is storedand sent to the upstream TC module 230. Based on the upstream bandwidthgrant, the upstream TC module 230 controls the first upstream burstreceiver 251 to receive the upstream data sent by the ONU in bursts onthe first upstream channel, and controls the second upstream burstreceiver 252 to receive the upstream data sent by the ONU in bursts onthe second upstream channel.

Optionally, after obtaining the upstream bandwidth grant, before theupstream data arrives, the upstream TC module 230 separately resets thefirst upstream burst receiver 251 and the second upstream burst receiver252, to instruct the first upstream burst receiver 251 to start toreceive the upstream data transmitted by the ONU on the first upstreamchannel, and instruct the second upstream burst receiver 252 to start toreceive the upstream data transmitted by the ONU on the second upstreamchannel.

Further, the upstream TC module 230 may further identify, based on theupstream bandwidth grant, an ONU that transmits upstream data on thefirst upstream channel and an ONU that transmits upstream data on thesecond upstream channel, to further forward the upstream data.

Further, the upstream TC module 230 may further perform, based on theupstream bandwidth grant, authentication on the upstream data sent bythe ONU, to determine whether the PON system has an ONU that performsunauthorized access. For example, if detecting upstream data outside anupstream sending timeslot indicated by the upstream bandwidth grant, theupstream TC module 230 determines that the PON system has an ONU thatperforms unauthorized access. For another example, after receivingupstream data, the upstream TC module 230 searches the upstreambandwidth grant for a corresponding ONU identifier based on an upstreamsending timeslot in which a sending party (an ONU sending the upstreamdata) sends the upstream data, and if a found ONU identifier isinconsistent with an ONU identifier of the sending party, determinesthat the PON system has an ONU that performs unauthorized access. TheONU identifier is an LLID or an ONU ID allocated by the OLT. Forupstream data that fails to be authenticated, the OLT directly filtersthe upstream data, and for upstream data that has been authenticated,the OLT further parses the upstream data to obtain service informationincluded in the upstream data.

In this embodiment, the memory is used to provide the upstream bandwidthgrant for the upstream TC module, so that the upstream TC module cancontrol, based on the upstream bandwidth grant, the upstream burstreceiver to receive the upstream data. Therefore, the upstream data isreceived more accurately. In addition, the upstream TC module mayfurther perform authentication on the received upstream data by usingthe upstream bandwidth grant, to prevent an ONU that performsunauthorized access from affecting the PON system.

FIG. 5 is a schematic structural diagram of an ONU according to anembodiment of this application. In this embodiment, an example in whichthe ONU is used in the PON system shown in FIG. 1 is used fordescription. The ONU includes: a downstream TC module 510, at least oneDBA response module 520, an upstream TC module 530, a downstreamreceiver 540, a first upstream burst transmitter 551, and a secondupstream burst transmitter 552.

The downstream receiver 540 is configured to receive, on a downstreamchannel, downstream data sent by an OLT (in a broadcast manner). Thedownstream data is transmitted on the downstream channel in a form of anoptical carrier signal.

The downstream data includes an upstream bandwidth grant used to controlthe ONU to send upstream data. Optionally, when the ONU is used in aGPON system, a BWmap message sent by the OLT carries the upstreambandwidth grant; or when the ONU is used in an EPON system, a Gatemessage sent by the OLT carries the upstream bandwidth grant.

Optionally, the downstream data further includes downstream service datathat the ONU requests to obtain, for example, video data and voice datathat the ONU requests to obtain.

After obtaining the downstream data, the downstream receiver 540provides the downstream data for the downstream TC module 510 connectedto the downstream receiver 540.

In a possible implementation, after obtaining the downstream data, thedownstream TC module 510 recovers the upstream bandwidth grant anddownstream service data included in the downstream data, provides thedownstream service data for a terminal device connected to thedownstream TC module 510, and provides the identified upstream bandwidthgrant for the DBA response module 520 connected to the downstream TCmodule 510.

The DBA response module 520 corresponds to the DBA scheduling module ofthe OLT in the foregoing embodiment, and is configured to control, basedon the obtained upstream bandwidth grant, the ONU to send upstream dataon an upstream channel.

As shown in FIG. 5, the DBA response module 520 is further connected tothe upstream TC module 530, and is configured to control, based on anupstream bandwidth grant included in the downstream data, the upstreamTC module 530 to send upstream data.

Different from the prior art in which the ONU sends upstream data onlyon one upstream channel, in this embodiment, the ONU sends upstream datato the OLT on two upstream channels.

Optionally, the downstream data includes a first upstream bandwidthgrant and a second upstream bandwidth grant. The DBA response module 520controls, based on the first upstream bandwidth grant, the upstream TCmodule 530 to send the upstream data on a first upstream channel, andcontrols, based on the second upstream bandwidth grant, the upstream TCmodule 530 to send the upstream data on a second upstream channel.

Optionally, the upstream TC module 530 is further configured to receivean upstream bandwidth request sent by each DBA response module 520, andreports the upstream bandwidth request on an upstream channelcorresponding to the DBA response module 520. The upstream bandwidthrequest is obtained by the DBA response module 520 by collectingstatistics on data packets in a sending queue.

To send upstream data on two channels, the upstream TC module 530 isconnected to the first upstream burst transmitter 551 and the secondupstream burst transmitter 552, sends upstream data on the firstupstream channel by using the first upstream burst transmitter 551, andsends upstream data on the second upstream channel by using the secondupstream burst transmitter 552.

Optionally, when the upstream TC module 530 needs to send upstream dataon the first upstream channel, the upstream TC module 530 sends anenabling signal to the first upstream burst transmitter 551corresponding to the first upstream channel, to trigger the firstupstream burst transmitter 551 to send the upstream data. When theupstream TC module 530 needs to send upstream data on the secondupstream channel, the upstream TC module 530 sends an enabling signal tothe second upstream burst transmitter 552 corresponding to the secondupstream channel, to trigger the second upstream burst transmitter 552to send the upstream data.

In this embodiment, a registration function is disabled on the firstupstream channel, the registration function is enabled on the secondupstream channel, and enabling and disabling of the registrationfunction on the first upstream channel and the second upstream channelare controlled by the OLT.

A registration response packet can be transmitted only on an upstreamchannel on which the registration function is enabled, and differentupstream channels do not conflict with each other. Therefore,optionally, the ONU selects the first upstream channel on which theregistration function is disabled, to transmit upstream service data,and selects the second upstream channel on which the registrationfunction is enabled, to transmit the registration response packet.Alternatively, based on a service delay requirement, the ONU selects thefirst upstream channel on which the registration function is disabled,to transmit upstream service data corresponding to a low-delay service(a service with a relatively high delay requirement), and selects thesecond upstream channel on which the registration function is enabled,to transmit the registration response packet and upstream service datacorresponding to a high-delay service (a service having a relatively lowdelay requirement).

Obviously, two upstream channels are configured, and it is configuredthat the registration function is disabled on the first upstream channeland the registration function is enabled on the second upstream channel,so that when an unregistered ONU in the PON system sends theregistration response packet on the second upstream channel, aregistered ONU can still send upstream service data on the firstupstream channel, to prevent ONU registration from affecting sending ofupstream data of a service and satisfy a system delay requirement of alow-delay service.

It should be noted that because the downstream channel, the firstupstream channel, and the second upstream channel share one ODN in awavelength division multiplexing manner, and wavelengths of the firstupstream channel and the second upstream channel are different, awavelength multiplexer/demultiplexer 560 is further disposed in the ONU,and is configured to combine or split an optical carrier signal on theupstream and downstream channels.

In a possible implementation, the upstream bandwidth grant sent by theOLT on the downstream channel is obtained by multiplexing the firstupstream bandwidth grant and the second upstream bandwidth grant.Correspondingly, after receiving the upstream bandwidth grant, the ONUneeds to demultiplex the upstream bandwidth grant, and send upstreamdata on a corresponding upstream channel based on the first upstreambandwidth grant and the second upstream bandwidth grant obtained bydemultiplexing. Based on the ONU shown in FIG. 5, as shown in FIG. 6,the ONU includes a first DBA response module 521, a second DBA responsemodule 522, and a demultiplexing module 570.

The demultiplexing module 570 corresponds to the multiplexing module ofthe OLT in the foregoing embodiment, and is configured to: obtain theupstream bandwidth grant received by the downstream TC module 510, anddemultiplex the upstream bandwidth grant to obtain the first upstreambandwidth grant and the second upstream bandwidth grant.

Further, the demultiplexing module 570 is further connected to the firstDBA response module 521 and the second DBA response module 522, and isconfigured to: provide the first upstream bandwidth grant obtained bydemultiplexing for the first DBA response module 521, and provide thesecond upstream bandwidth grant obtained by demultiplexing for thesecond DBA response module 522.

Optionally, the demultiplexing module 570 obtains the first upstreambandwidth grant and the second upstream bandwidth grant bydemultiplexing based on an upstream channel identifier included in the(multiplexed) upstream bandwidth grant. The first upstream bandwidthgrant corresponds to an upstream channel identifier of a first upstreamchannel, and the second upstream bandwidth grant corresponds to anupstream channel identifier of a second upstream channel. Further, thedemultiplexing module 570 sends the first upstream bandwidth grant andthe second upstream bandwidth grant to corresponding DBA responsemodules.

As shown in FIG. 6, the first DBA response module 521 is connected tothe demultiplexing module 570, and is configured to control, based onthe first upstream bandwidth grant, the upstream TC module 530 to sendthe upstream data on the first upstream channel.

The second DBA response module 522 is connected to the demultiplexingmodule 570, and is configured to control, based on the second upstreambandwidth grant, the upstream TC module 530 to send the upstream data onthe second upstream channel.

In a possible implementation, the first upstream channel on which aregistration function is disabled is only used to transmit upstreamservice data, and the second upstream channel on which the registrationfunction is enabled is only used to transmit a registration responsepacket.

For an ONU in a registered state in the PON system, the upstream TCmodule 530 of the ONU sends a first enabling signal to the firstupstream burst transmitter 551 based on an upstream sending timeslot inthe first upstream bandwidth grant, to trigger the first upstream bursttransmitter 551 to send the upstream service data to the OLT on thefirst upstream channel.

For an ONU in an unregistered state in the PON system, the upstream TCmodule 530 of the ONU sends a second enabling signal to the secondupstream burst transmitter 552 based on a registration timeslot in thesecond upstream bandwidth grant, to trigger the second upstream bursttransmitter 552 to send the registration response packet to the OLT onthe second upstream channel.

In other words, when the first upstream channel on which theregistration function is disabled is only used to transmit upstreamservice data, and the second upstream channel on which the registrationfunction is enabled is only used to transmit the registration responsepacket, registered ONUs in the PON system all send upstream service datato the OLT on the first upstream channel, and unregistered ONUs all sendregistration response packets to the OLT on the second upstream channel.The upstream service data and the registration response packets aretransmitted on different upstream channels, to prevent an ONUregistration process from affecting a process of sending the upstreamservice data.

In another possible implementation, the first upstream channel on whichthe registration function is disabled is used to transmit first upstreamservice data, and the second upstream channel on which the registrationfunction is enabled is used to transmit the registration response packetand second upstream service data.

For an ONU in a registered state in the PON system, the upstream TCmodule 530 of the ONU sends a third enabling signal to the firstupstream burst transmitter 551 based on a first upstream sendingtimeslot in the first upstream bandwidth grant, to trigger the firstupstream burst transmitter 551 to send the first upstream service dataon the first upstream channel. At the same time, the upstream TC module530 sends a fourth enabling signal to the second upstream bursttransmitter 552 based on a second upstream sending timeslot in thesecond upstream bandwidth grant, to trigger the second upstream bursttransmitter 552 to send the second upstream service data on the secondupstream channel. A delay requirement of the first upstream service datais higher than a delay requirement of the second upstream service data.

For an ONU in an unregistered state in the PON system, the upstream TCmodule 530 of the ONU sends a second enabling signal to the secondupstream burst transmitter 552 based on a registration timeslot in thesecond upstream bandwidth grant, to trigger the second upstream bursttransmitter 552 to send the registration response packet on the secondupstream channel. It should be noted that when the unregistered ONUsends the registration response packet on the second upstream channel, aregistered ONU needs to stop sending the second upstream service data onthe second upstream channel, to prevent the registration response packetfrom conflicting with the second upstream service data on the secondupstream channel. Simply, in this embodiment, the first upstream channelis used to transmit upstream service data of a low-delay service, and inaddition to being used to perform ONU registration, the second upstreamchannel is further used to transmit upstream service data of ahigh-delay service. Therefore, two upstream channels are used totransmit upstream service data while it is ensured that ONU registrationdoes not affect the low-delay service, thereby further increasing atransmission rate of the upstream service data in the PON system.

It should be noted that only an example in which the first DBA responsemodule 521 and the second DBA response module 522 are connected to thesame upstream TC module 530 is used for description in the foregoingembodiment. In another possible implementation, the upstream TC module530 may be divided into two upstream TC submodules. The first DBAresponse module 521 and the second DBA response module 522 are connectedto respective upstream TC submodules of the first DBA response module521 and the second DBA response module 522, and send upstream data byusing the upstream TC submodules. This is not limited in the embodiment.

In the foregoing embodiment, an example in which the ONU includes thetwo DBA response modules is used for description. In another possibleimplementation, based on the ONU shown in FIG. 5, as shown in FIG. 7,the ONU includes a DBA response module 520 and a channel selectionmodule 580.

The DBA response module 520 is connected to the downstream TC module510, and is configured to: control, based on a received first upstreambandwidth grant, the upstream TC module 530 to send upstream servicedata, or control, based on a received second upstream bandwidth grant,the upstream TC module 530 to send a registration response packet.

One end of the channel selection module 580 is connected to the upstreamTC module 530, and the other end of the channel selection module 580 isconnected to the first upstream burst transmitter 551 and the secondupstream burst transmitter 552. After obtaining to-be-sent upstream data(the upstream service data or the registration response packet) by usingthe upstream TC module 530, the channel selection module 580 furtherdetermines, based on a registration status of the ONU, an upstream bursttransmitter selected to send upstream data.

When the ONU is in a registered state, the channel selection module 580selects the first upstream burst transmitter 551 to send the upstreamservice data generated by the upstream TC module 530 through framing andconvergence, or when the ONU is in an unregistered state, the channelselection module 580 selects the second upstream burst transmitter 552to send the registration response packet generated by the upstream TCmodule 530.

In this embodiment, based on a registration status of the ONU, when theONU is in the registered state, the channel selection module of the ONUdisables the second upstream burst transmitter (that is, disables thesecond upstream channel of the ONU) and sends the upstream service dataon the first upstream channel by using the enabled first upstream bursttransmitter; and when the ONU is in the unregistered state, disables thefirst upstream burst transmitter (that is, disables the first upstreamchannel of the ONU) and sends the registration response packet on thesecond upstream channel by using the enabled second upstream bursttransmitter, to dynamically perform energy conservation of the ONU.

When the ONU needs to simultaneously send upstream service data of alow-delay service and a high-delay service, to prevent ONU registrationfrom affecting the low-delay service, the ONU needs to separate a dataupstream process of the low-delay service from an ONU registrationprocess. In a possible implementation, based on the ONU shown in FIG. 6,as shown in FIG. 8, the ONU further includes a service classificationmodule 590.

The service classification module 590 classifies upper-layer servicesaccording to a preset classification criterion, and classifiesupper-layer services into a first class and a second class. A delayrequirement of a service belonging to the first class is higher than adelay requirement of a service belonging to the second class.

Optionally, the service classification module 590 is configured to:collect a delay requirement of each service and determine a serviceclass of the service based on the delay requirement.

Further, the service classification module 590 selects, based on aservice class to which each service belongs, a corresponding DBAresponse module (a corresponding upstream channel) to send upstreamservice data corresponding to the service.

Because a high-delay service is insensitive to a delay, that is, ONUregistration does not affect the high-delay service, when a serviceclass indicates that a service belongs to the first class (that is, theservice is a low-delay service), the service classification module 590transfers the service to the first DBA response module 521 forprocessing. The first DBA response module 521 controls the upstream TCmodule 530 to send, on a first upstream channel on which a registrationfunction is disabled, first upstream service data corresponding to theservice. When a service class indicates that a service belongs to thesecond class (that is, the service is a high-delay service), the serviceclassification module 590 transfers the service to the second DBAresponse module 522 for processing. The second DBA response module 522controls the upstream TC module 530 to send, on a second upstreamchannel on which the registration function is enabled, second upstreamservice data corresponding to the service.

Optionally, for upstream data sent on a same upstream channel, the ONUmay further sort services based on service priorities, andpreferentially send upstream data corresponding to a high-priorityservice. This is not limited in this embodiment.

In this embodiment, the ONU classifies services by using the serviceclassification module, selects the first upstream channel on which theregistration function is disabled, to send upstream data correspondingto a low-delay service, and selects the second upstream channel on whichthe registration function is enabled, to send upstream datacorresponding to a high-delay service, to ensure that the low-delayservice is not affected by ONU registration and satisfy a system delayrequirement of the low-delay service.

In the ONU shown in FIG. 5 to FIG. 8, the first upstream bursttransmitter 551 and the second upstream burst transmitter 552 are bothfixedly disposed in the ONU. However, in an actual use process, thesecond upstream burst transmitter 552 works only when registration isperformed or when the second upstream service data needs to be sent. Asa result, utilization of the second upstream burst transmitter 552 isrelatively low. To reduce manufacturing costs of the entire ONU, basedon the ONU shown in FIG. 5, in a possible implementation, as shown inFIG. 9, the ONU includes an optical module slot 910. The optical moduleslot 910 is used for a first optical module 911 or a second opticalmodule 912 to slot into.

The first optical module 911 includes at least the downstream receiver540 and the first upstream burst transmitter 551, and the second opticalmodule 912 includes at least the downstream receiver 540 and the secondupstream burst receiver 551. To be specific, when the first opticalmodule 911 is slot into the optical module slot 910, the first opticalmodule 911 receives downstream data on a downstream channel by using thedownstream receiver 540, and sends upstream data on a first upstreamchannel by using the first upstream burst transmitter 551. When thesecond optical module 912 is slot into the optical module slot 910, thesecond optical module 912 receives downstream data on the downstreamchannel, and sends upstream data on a second upstream channel by usingthe second upstream burst transmitter 552. Because a registrationfunction is disabled on the first upstream channel and the registrationfunction is enabled on the second upstream channel, in an unregisteredONU in the PON system, the second optical module 912 is slot into theoptical module slot 910, so that after receiving, on the downstreamchannel, the downstream data including a registration timeslot, theunregistered ONU can send a registration response packet to the OLT byusing the second upstream burst transmitter 552 in the second opticalmodule 912, to complete registration and activation. After the ONUcompletes registration, the second optical module 912 is removed, andthe first optical module 911 is slot into the optical module slot 910,so that after receiving, on the downstream channel, the downstream dataincluding an upstream sending timeslot, a registered ONU can sendupstream service data to the OLT by using the first upstream bursttransmitter 551 in the first optical module 911.

It should be noted that after the second optical module 912 is removedand before the first optical module 911 is slot into the optical moduleslot 910, the ONU may be out of synchronization because the ONUreceives, within a particular time period, no downstream data sent bythe OLT. As a result, the ONU exits from a normal working state. Toenable the ONU to recover the normal working state, after the secondoptical module 911 is slot into the optical module slot 910, the OLTdelivers registration information to the ONU on the downstream channel,so that the ONU recovers the normal working state based on theregistration information.

Obviously, when installing the ONU, an installation person only needs toperform ONU registration in an ONU registration stage by using thesecond optical module 912, and after completing the ONU registration,slots the first optical module 910 into the ONU, to complete ONUinstallation. An installation person can complete installation ofdifferent ONUs by using the same second optical module 912, to reduceONU manufacturing costs.

In another possible implementation, the wavelengthmultiplexer/demultiplexer 560, the downstream TC module 510, the DBAresponse module 520, the upstream TC module 530, and the second opticalmodule 912 may further form an ONU registration device dedicated forregistration, and an SN or a MAC address of the ONU registration deviceis set to be modifiable. When a newly added ONU (including the firstoptical module 910) needs to be registered, the ONU registration deviceobtains an SN or a MAC address of the newly added ONU and the newlyadded ONU accesses the PON system. When receiving the downstream datasent by the OLT on the downstream channel, the ONU registration devicesends the registration response packet (including an SN or a MAC addressof the newly added ONU) on the second upstream channel based on aregistration timeslot included in the downstream data, to completeregistration and activation. After the ONU registration device completesregistration based on an SN or a MAC address of the newly added ONU, theONU registration device is removed and the newly added ONU accesses thePON system. Because the ONU registration device already performsregistration by using the SN or the MAC address of the newly added ONU,registration is completed when the newly added ONU accesses the PONsystem, and upstream service data can be sent by using the firstupstream burst transmitter 551 in the first optical module 910.

It should be noted that after the ONU registration device is removed andthe newly added ONU accesses the PON system, the newly added ONU may bein an initial state. To enable the newly added ONU to normally work, theOLT delivers registration information to the ONU on the downstreamchannel, so that the ONU recovers a normal working state based on theregistration information.

In this embodiment, the downstream receiver and the first upstream bursttransmitter are integrated into the first optical module, and thedownstream receiver and the second upstream burst transmitter areintegrated into the second optical module, so that different newly addedONUs all can complete ONU registration by using the same second opticalmodule, thereby improving utilization of the second upstream bursttransmitter and reducing ONU manufacturing costs.

In the ONU shown in FIG. 9, the second upstream channel is only used toperform ONU registration, and all upstream service data is transmittedon the first upstream channel. When a data volume of the upstreamservice data is relatively large, transmission pressure is excessivelylarge on the first upstream channel, and a low-delay service isaffected. To reduce transmission pressure on a single upstream channel,based on the ONU shown in FIG. 5, as shown in FIG. 10, the ONU includesa first optical module slot 1011 and a second optical module slot 1012.The first optical module slot 1011 is used for a first optical module1021 to slot into, and the second optical module slot 1012 is used for asecond optical module 1022 to slot into.

The first optical module 1021 includes at least the first upstream bursttransmitter 551, and the second optical module 1022 includes at leastthe downstream receiver 540 and the second upstream burst transmitter552.

For a newly added ONU, the second optical module 1022 is slot into thesecond optical module slot 1012, and the ONU accesses the PON system, sothat the ONU may receive downstream data by using the downstreamreceiver 540 in the second optical module 1022, and completeregistration and activation on a second upstream channel based on aregistration timeslot included in the downstream data. When the ONU isonly configured to transmit upstream service data of a high-delayservice, after completing the registration on the second upstreamchannel, the ONU further sends the upstream service data on the secondupstream channel. Because the high-delay service is insensitive to adelay, although the newly added ONU performs device registration on thesecond upstream channel, the registered ONU is not severely affected.

When the ONU needs to transmit upstream service data of a low-delayservice, to prevent ONU registration from affecting the low-delayservice, the first optical module 1021 needs to be slot into the firstoptical module slot 1011. After the first optical module 1021 is slotinto the ONU, the ONU transmits, by using the second upstream bursttransmitter 552 in the second optical module 1022, second upstreamservice data corresponding to a high-delay service, and transmits, byusing the first upstream burst transmitter 551 in the first opticalmodule 1021, first upstream service data corresponding to a low-delayservice, to offload the upstream service data. At the same time, becausethe newly added ONU performs registration on the second upstreamchannel, ONU registration does not affect transmission of the upstreamservice data on the first upstream channel.

It should be noted that when the optical module shown in FIG. 9 and FIG.10 includes both the upstream burst transmitter and the downstreamreceiver, the optical module further needs to include a wavelengthmultiplexer/demultiplexer, to combine or split a received opticalcarrier signal. This is not limited in this embodiment of thisapplication.

FIG. 11 is a flowchart of a data exchange process in a PON systemaccording to an embodiment of this application. The PON system includesan OLT and at least two ONUs, the OLT is connected to each ONU by usingan ODN, and the OLT and the at least two ONUs exchange data on onedownstream channel and two upstream channels in the ODN.

Step 1110: The OLT sends downstream data to each ONU on a downstreamchannel, where the downstream data includes an upstream bandwidth grant,and the upstream bandwidth grant is used to control the ONU to sendupstream data.

Optionally, the upstream bandwidth grant is generated by at least oneDBA scheduling module of the OLT.

Optionally, the downstream data includes a first upstream bandwidthgrant and a second upstream bandwidth grant, the first upstreambandwidth grant is used to control the ONU to send the upstream data ona first upstream channel, the second upstream bandwidth grant is used tocontrol the ONU to send the upstream data on a second upstream channel,and the upstream data sent by the ONU includes upstream service data ora registration response packet.

Optionally, if the PON system is a GPON system, the upstream bandwidthgrant is carried in a BWmap message; or if the PON system is an EPONsystem, the upstream bandwidth grant is carried in a Gate message.

Step 1120: The ONU receives the downstream data on the downstreamchannel.

Correspondingly, each ONU in the PON system receives, on the downstreamchannel, the downstream data sent by the OLT in a broadcast manner.

Step 1130: The ONU sends the upstream data on a first upstream channelor a second upstream channel based on the upstream bandwidth grantincluded in the downstream data.

The ONU further obtains the upstream bandwidth grant included in thedownstream data, and sends the upstream data to the OLT on the firstupstream channel or the second upstream channel based on a registrationstatus of the ONU. A registration function is disabled on the firstupstream channel, the registration function is enabled on the secondupstream channel, and the registration function is used to register anunregistered ONU.

Optionally, when the ONU is in an unregistered state and the obtainedupstream bandwidth grant includes a registration timeslot, the ONU sendsa registration response packet to the OLT in the registration timesloton the second upstream channel on which the registration function isenabled.

Optionally, when the ONU is in a registered state and the obtainedupstream bandwidth grant includes an upstream sending timeslot, the ONUsends upstream service data to the OLT in the upstream sending timesloton the first upstream channel on which the registration function isdisabled, or the ONU sends upstream service data to the OLT in theupstream sending timeslot on both the first upstream channel and thesecond upstream channel.

In this embodiment, the ONU sends upstream service data and performs ONUregistration on different upstream channels based on the upstreambandwidth grant generated by the OLT, to prevent ONU registration fromaffecting sending of the upstream service data and satisfy a systemdelay requirement of a low-delay service.

It should be noted that the downstream channel, the first upstreamchannel, and the second upstream channel share one ODN in a wavelengthdivision multiplexing manner, and wavelengths of the first upstreamchannel and the second upstream channel are different, to avoidinterference between the first upstream channel and the second upstreamchannel.

Step 1140: The OLT receives, on the first upstream channel and thesecond upstream channel, the upstream data sent by each ONU.

Correspondingly, the OLT receives, on the first upstream channel and thesecond upstream channel, the upstream data sent by each ONU. Theupstream data includes a registration response packet sent on the secondupstream channel and upstream service data sent on the first upstreamchannel and/or the second upstream channel.

Optionally, when the OLT receives upstream service data sent by aregistered ONU, the OLT parses the upstream service data, and furtherfeeds back corresponding downstream data to the ONU on the downstreamchannel. When the OLT receives a registration response packet sent by anunregistered ONU, the OLT registers the unregistered ONU.

In a possible implementation, the downstream data sent by the OLT on thedownstream channel includes the first upstream bandwidth grant and thesecond upstream bandwidth grant. After receiving the downstream data,the ONU sends the upstream data to the OLT on the first upstream channelbased on the first upstream bandwidth grant, and/or sends the upstreamdata to the OLT on the second upstream channel based on the secondupstream bandwidth grant. The following provides descriptions by usingan embodiment as an example.

FIG. 12 is a flowchart of a data exchange process in a PON systemaccording to another embodiment of this application.

Step 1201: An OLT generates a first upstream bandwidth grant and asecond upstream bandwidth grant.

In this embodiment, in the PON system, a registration function isdisabled on a first upstream channel and the registration function isenabled on a second upstream channel. In other words, an unregisteredONU in the PON system completes registration and activation on thesecond upstream channel. Correspondingly, the first upstream bandwidthgrant generated by the OLT is used to instruct a registered ONU to sendupstream service data on the first upstream channel, and the secondupstream bandwidth grant generated by the OLT is used to instruct anunregistered ONU to send a registration response packet on the secondupstream channel in a registration period, or the second upstreambandwidth grant is used to instruct a registered ONU to send upstreamservice data on the second upstream channel in a non-registrationperiod.

Optionally, the OLT includes a first DBA scheduling module and a secondDBA scheduling module, generates the first upstream bandwidth grant byusing the first DBA scheduling module, and generates the second upstreambandwidth grant by using the second DBA scheduling module.

In a possible implementation, when the first upstream channel isconfigured to transmit only upstream service data, and the secondupstream channel is configured to transmit only a registration responsepacket, the OLT generates the first upstream bandwidth grant includingan upstream sending timeslot, and generates the second upstreambandwidth grant including a registration timeslot. The first upstreambandwidth grant is used to instruct a registered ONU in the PON systemto send upstream service data on the first upstream channel in theupstream sending timeslot. The second upstream bandwidth grant is usedto instruct an unregistered ONU in the PON system to send a registrationresponse packet on the second upstream channel in the registrationtimeslot.

In another possible implementation, when the first upstream channel isconfigured to transmit first upstream service data, and the secondupstream channel is configured to transmit a registration responsepacket and second upstream service data, the OLT generates the firstupstream bandwidth grant including a first upstream sending timeslot,and generates the second upstream bandwidth grant including a secondupstream sending timeslot and a registration timeslot. The firstbandwidth grant is used to instruct a registered ONU in the PON systemto send the first upstream service data on the first upstream channel inthe first upstream sending timeslot. The second bandwidth grant is usedto instruct a registered ONU to send the second upstream service data onthe second upstream channel in a non-registration period (that is, anon-quiet zone) (based on the second upstream sending timeslot), or thesecond bandwidth grant is used to instruct an unregistered ONU to sendthe registration response packet on the second upstream channel in aregistration period (based on the registration timeslot). A delayrequirement of the first upstream service data is higher than a delayrequirement of the second upstream service data.

It should be noted that enabling and disabling of the registrationfunction on the first upstream channel and the second upstream channelare flexibly configured by the OLT. To be specific, the OLT mayconfigure enabling of the registration function on the first upstreamchannel and configure disabling of the registration function on thesecond upstream channel. Alternatively, the OLT may configure disablingof the registration function on the first upstream channel, andconfigure enabling of the registration function on the second upstreamchannel. In this embodiment of this application, only an example inwhich the registration function is disabled on the first upstreamchannel and the registration function is enabled on the second upstreamchannel is used for description. However, this is not limited.

Optionally, the OLT obtains channel transmission quality of the firstupstream channel and the second upstream channel at predeterminedintervals. When the channel transmission quality of the first upstreamchannel is better than the channel transmission quality of the secondupstream channel, the OLT controls the registration function to bedisabled on the first upstream channel, and controls the registrationfunction to be enabled on the second upstream channel. When the channeltransmission quality of the second upstream channel is better than thechannel transmission quality of the first upstream channel, the OLTcontrols the registration function to be disabled on the second upstreamchannel, and controls the registration function to be enabled on thefirst upstream channel.

Optionally, upstream data is sent on the first upstream channel and thesecond upstream channel in bursts. Therefore, to enable the OLT to learnof an arriving time of the upstream data so that an upstream burstreceiver of the OLT makes preparations for receiving data before theupstream data arrives, the OLT stores the generated first upstreambandwidth grant and second upstream bandwidth grant, and controls, basedon the first upstream bandwidth grant and the second upstream bandwidthgrant, the corresponding upstream burst receiver to receive the upstreamdata.

Step 1202: The OLT multiplexes the first upstream bandwidth grant andthe second upstream bandwidth grant, to obtain the multiplexed upstreambandwidth grant.

Optionally, a multiplexing module is disposed in the OLT, and themultiplexing module performs multiplexing and convergence on theupstream bandwidth grants generated by the OLT.

Because the first upstream bandwidth grant and the second upstreambandwidth grant are sent to the ONU on a same downstream channel afterbeing multiplexed, in a process of multiplexing the first upstreambandwidth grant and the second upstream bandwidth grant, the OLT needsto add corresponding upstream channel identifiers to the first upstreambandwidth grant and the second upstream bandwidth grant, and thenmultiplexes the upstream bandwidth grants to which the upstream channelidentifiers are added. In this way, the ONU can identify the firstupstream bandwidth grant and the second upstream bandwidth grant, anddetermine upstream channels corresponding to different upstreambandwidth grants. Optionally, the OLT may alternatively directlygenerate the first upstream bandwidth grant and the second upstreambandwidth grant carrying upstream channel identifiers. This is notlimited in this embodiment of this application.

In a possible implementation, when the OLT is used in a GPON system, theOLT separately adds upstream channel identifiers to a first BWmapmessage (that is, a message carrying the first upstream bandwidth grant)and a second BWmap message (that is, a message carrying the secondupstream bandwidth grant).

In a possible implementation, when the OLT is used in an EPON system,the OLT separately adds upstream channel identifiers to a first Gatemessage (that is, a message carrying the first upstream bandwidth grant)and a second Gate message (that is, a message carrying the secondupstream bandwidth grant).

Step 1203: The OLT sends downstream data to each ONU on a downstreamchannel, where the downstream data includes the multiplexed upstreambandwidth grant.

Optionally, after performing upper-layer service adaptation, GEMencapsulation, TC framing, and physical layer adaptation, the OLTgenerates the downstream data, and controls a built-in downstreamtransmitter to send the downstream data on the downstream channel. Theupper-layer service adaptation includes user data adaptation. OMCIadaptation, and the like.

Step 1204: The ONU receives the downstream data on the downstreamchannel.

Correspondingly, each ONU in the PON system receives, on the downstreamchannel, the downstream data sent by the OLT in a broadcast manner.

Step 1205: The ONU demultiplexes the received upstream bandwidth grant,to obtain the first upstream bandwidth grant and the second upstreambandwidth grant.

After receiving the downstream data, the ONU obtains the multiplexedupstream bandwidth grant included in the downstream data, anddemultiplexes the upstream bandwidth grant to obtain the first upstreambandwidth grant and the second upstream bandwidth grant.

Optionally, the ONU obtains the multiplexed upstream bandwidth grant,and demultiplexes the multiplexed upstream bandwidth grant based on theupstream channel identifiers included in the upstream bandwidth grant,to obtain the first upstream bandwidth grant used to control the firstupstream channel and the second upstream bandwidth grant used to controlthe second upstream channel.

Step 1206: The ONU sends upstream data on a first upstream channel basedon the first upstream bandwidth grant, and/or sends upstream data on asecond upstream channel based on the second upstream bandwidth grant.

In a possible implementation, when the first upstream channel is used totransmit upstream service data, and the second upstream channel is usedto transmit only a registration response packet, a registered ONU sendsthe upstream service data on the first upstream channel based on anupstream sending timeslot included in the first upstream bandwidthgrant: and an unregistered ONU sends the registration response packet onthe second upstream channel based on a registration timeslot included inthe second upstream bandwidth grant.

In another possible implementation, when the first upstream channel isused to transmit first upstream service data, and the second upstreamchannel is used to transmit a registration response packet and secondupstream service data, a registered ONU sends the first upstream servicedata on the first upstream channel based on a first upstream sendingtimeslot included in the first upstream bandwidth grant, and sends thesecond upstream service data on the second upstream channel based on asecond upstream sending timeslot included in the second upstreambandwidth grant; and an unregistered ONU sends the registration responsepacket to the OLT on the second upstream channel based on a registrationtimeslot in the second upstream bandwidth grant, to completeregistration and activation.

A same ONU needs to execute a plurality of services and differentservices have different delay requirements. Optionally, to ensure thatthe PON system satisfies a delay requirement of a low-delay service,before sending upstream data on two upstream channels, a registered ONUcollects a delay requirement of each upper-layer service, and determinesa service class of the service based on the delay requirement of theservice. When a service class indicates that a service belongs to afirst class, the ONU determines to send, on the first upstream channel,upstream data corresponding to the service; when a service classindicates that a service belongs to a second class, the ONU determinesto send, on the second upstream channel, upstream data corresponding tothe service.

It should be noted that for upstream data sent on a same upstreamchannel, the ONU may further sort services based on service priorities,and preferentially send upstream data corresponding to a high-priorityservice. This is not limited in this embodiment.

Step 1207: The OLT receives, on the first upstream channel and thesecond upstream channel, the upstream data sent by each ONU.

Optionally, a first upstream burst receiver and a second upstream burstreceiver are disposed in the OLT. The OLT receives, on the firstupstream channel by using the first upstream burst receiver, upstreamservice data sent by a registered ONU, and receives, on the secondupstream channel by using the second upstream burst receiver, upstreamservice data sent by a registered ONU or a registration response packetsent by an unregistered ONU.

Optionally, when the OLT stores the generated upstream bandwidth grant,the OLT resets the built-in upstream burst receiver before upstream dataarrives, to instruct the upstream burst receiver to start to receive theupstream data transmitted by the ONU on the first upstream channel andthe second upstream channel.

Optionally, the OLT may further identify, based on the upstreambandwidth grant, an ONU that transmits upstream data on the firstupstream channel and an ONU that transmits upstream data on the secondupstream channel, to further forward the upstream data.

Optionally, the OLT may further perform, based on the upstream bandwidthgrant, authentication on the upstream data sent by the ONU, to determinewhether the PON system has an ONU that performs unauthorized access. Forexample, if detecting upstream data outside an upstream sending timeslotindicated by the upstream bandwidth grant, the OLT determines that thePON system has an ONU that performs unauthorized access. For anotherexample, after receiving upstream data, the OLT searches the upstreambandwidth grant for a corresponding ONU identifier based on an upstreamsending timeslot in which a sending party (an ONU sending the upstreamdata) sends the upstream data, and if a found ONU identifier isinconsistent with an ONU identifier of the sending party, determinesthat the PON system has an ONU that performs unauthorized access. TheONU identifier is an LLID or an ONU ID allocated by the OLT. Forupstream data that fails to be authenticated, the OLT directly filtersthe upstream data, and for upstream data that has been authenticated,the OLT further parses the upstream data to obtain service informationincluded in the upstream data.

In this embodiment, the OLT generates the first upstream bandwidth grantand the second upstream bandwidth grant respectively used to control thefirst upstream channel and the second upstream channel, and multiplexesthe first upstream bandwidth grant and the second upstream bandwidthgrant, to provide the multiplexed upstream bandwidth grant for each ONUon the downstream channel. In this way, the ONU can separately controldata sending on the first upstream channel and the second upstreamchannel based on the received upstream bandwidth grant, to ensure thatthe upstream data sequentially reaches the OLT through the firstupstream channel and the second upstream channel, and avoid a conflictbetween the upstream data.

In this embodiment, the OLT controls, by using the generated upstreambandwidth grant, the upstream burst receiver to receive upstream data,so that the upstream data is received more accurately. At the same time,the OLT performs authentication on the received upstream data by usingthe upstream bandwidth grant, to prevent an ONU that performsunauthorized access from affecting the PON system.

Further embodiments of the present disclosure are provided in thefollowing. It should be noted that the numbering used in the followingsection does not necessarily need to comply with the numbering used inthe previous sections.

Embodiment 1

A passive optical network (PON) system, wherein the system comprises: anoptical line terminal (OLT) and at least two optical network units(ONUs), the OLT is connected to each ONU by using an opticaldistribution network (ODN), and the OLT and the at least two ONUsexchange data on one downstream channel and two upstream channels; theOLT sends downstream data to each ONU on the downstream channel, whereinthe downstream data comprises an upstream bandwidth grant, and theupstream bandwidth grant is used to control the ONU to send upstreamdata; the ONU receives the downstream data on the downstream channel,and sends the upstream data on a first upstream channel or a secondupstream channel based on the upstream bandwidth grant comprised in thedownstream data; and the OLT receives, on the first upstream channel andthe second upstream channel, the upstream data sent by each ONU, whereina registration function is disabled on the first upstream channel, theregistration function is enabled on the second upstream channel, and theregistration function is used to register an unregistered ONU.

Embodiment 2

The system according to embodiment 1, wherein the downstream datacomprises a first upstream bandwidth grant and a second upstreambandwidth grant, the first upstream bandwidth grant is used to controlthe ONU to send upstream data on the first upstream channel, and thesecond upstream bandwidth grant is used to control the ONU to sendupstream data on the second upstream channel.

Embodiment 3

The system according to embodiment 2, wherein the OLT generates thefirst upstream bandwidth grant and the second upstream bandwidth grant,and multiplexes the first upstream bandwidth grant and the secondupstream bandwidth grant to obtain the multiplexed upstream bandwidthgrant; and the ONU demultiplexes the received upstream bandwidth grantto obtain the first upstream bandwidth grant and the second upstreambandwidth grant; and sends upstream data on the first upstream channelbased on the first upstream bandwidth grant, and sends upstream data onthe second upstream channel based on the second upstream bandwidthgrant.

Embodiment 4

The system according to embodiment 2 or 3, wherein the first upstreamchannel is used to transmit upstream service data, and the secondupstream channel is used to transmit a registration response packet; theOLT generates the first upstream bandwidth grant comprising an upstreamsending timeslot, and generates the second upstream bandwidth grantcomprising a registration timeslot; and when the ONU is in a registeredstate, the ONU sends the upstream service data to the OLT on the firstupstream channel based on the upstream sending timeslot in the firstupstream bandwidth grant; or when the ONU is in an unregistered state,the ONU sends a registration response packet to the OLT on the secondupstream channel based on the registration timeslot in the secondupstream bandwidth grant.

Embodiment 5

The system according to embodiment 2 or 3, wherein the first upstreamchannel is used to transmit first upstream service data, the secondupstream channel is used to transmit a registration response packet andsecond upstream service data, and a delay requirement of the firstupstream service data is higher than a delay requirement of the secondupstream service data; the OLT generates the first upstream bandwidthgrant comprising a first upstream sending timeslot, and generates thesecond upstream bandwidth grant comprising a second upstream sendingtimeslot and a registration timeslot; and when the ONU is in aregistered state, the ONU sends the first upstream service data to theOLT on the first upstream channel based on the first upstream sendingtimeslot in the first upstream bandwidth grant, and sends the secondupstream service data to the OLT on the second upstream channel based onthe second upstream sending timeslot in the second upstream bandwidthgrant; or when the ONU is in an unregistered state, the ONU sends aregistration response packet to the OLT on the second upstream channelbased on the registration timeslot in the second upstream bandwidthgrant.

Embodiment 6

The system according to any one of embodiments 1 to 5, wherein the OLTobtains channel transmission quality of the first upstream channel andthe second upstream channel; and when the channel transmission qualityof the first upstream channel is better than the channel transmissionquality of the second upstream channel, the OLT controls theregistration function to be disabled on the first upstream channel andcontrols the registration function to be enabled on the second upstreamchannel.

Embodiment 7

The system according to any one of embodiments 1 to 5, wherein the OLTstores the generated upstream bandwidth grant; and the OLT controlsreceiving of the upstream data based on the upstream bandwidth grant,and/or performs, based on the upstream bandwidth grant, authenticationand parsing on the upstream data sent by each ONU.

Embodiment 8

The system according to any one of embodiments 1 to 5, wherein the ONUdetermines a service class of each service based on a delay requirementof the service; and when the service class indicates that the servicebelongs to a first class, the ONU sends, on the first upstream channel,upstream data corresponding to the service; or when the service classindicates that the service belongs to a second class, the ONU sends, onthe second upstream channel, upstream data corresponding to the service,wherein a delay requirement of a service belonging to the first class ishigher than a delay requirement of a service belonging to the secondclass.

Embodiment 9

The system according to any one of embodiments 1 to 5, wherein if thesystem is a gigabit-capable passive optical network (GPON) system, abandwidth map (BWmap) message carries the upstream bandwidth grant; orif the system is an Ethernet passive optical network EPON system, a Gatemessage carries the upstream bandwidth grant.

Embodiment 10

The system according to embodiment 9, wherein when the BWmap messagecarries the upstream bandwidth grant, a predetermined bit of apredetermined field in the BWmap message is used to identify an upstreamchannel corresponding to the BWmap message; and when the Gate messagecarries the upstream bandwidth grant, a channel identifier field newlyadded to the Gate message is used to identify an upstream channelcorresponding to the Gate message, or operation code of the Gate messageis used to identify an upstream channel corresponding to the Gatemessage, wherein the predetermined field is a start time field or agrant size field, and the predetermined bit is a maximum of 1 bit or amaximum of 2 bits of the predetermined field.

Embodiment 11

The system according to any one of embodiments 1 to 5, wherein thedownstream channel, the first upstream channel, and the second upstreamchannel share the ODN in a wavelength division multiplexing manner, andwavelengths of the first upstream channel and the second upstreamchannel are different.

Embodiment 12

An optical line terminal (OLT), wherein the OLT comprises: at least onedynamic bandwidth allocation (DBA) scheduling module, a downstreamtransmission convergence TC module, an upstream TC module, a downstreamtransmitter, a first upstream burst receiver, and a second upstreamburst receiver, wherein the DBA scheduling module is configured togenerate an upstream bandwidth grant, wherein the upstream bandwidthgrant is used to control each optical network unit (ONU) to sendupstream data; the downstream TC module is connected to the DBAscheduling module, and is configured to generate, through downstreamframing and convergence, downstream data comprising the upstreambandwidth grant; the downstream transmitter is connected to thedownstream TC module, and is configured to send the downstream data toeach ONU on a downstream channel; the upstream TC module is connected tothe first upstream burst receiver, and is configured to receive, byusing the first upstream burst receiver, the upstream data sent by eachONU on a first upstream channel; and the upstream TC module is furtherconnected to the second upstream burst receiver, and is configured toreceive, by using the second upstream burst receiver, the upstream datasent by each ONU on a second upstream channel, wherein a registrationfunction is disabled on the first upstream channel, the registrationfunction is enabled on the second upstream channel, and the registrationfunction is used to register the unregistered ONU.

Embodiment 13

The OLT according to embodiment 12, wherein the downstream datacomprises a first upstream bandwidth grant and a second upstreambandwidth grant, the first upstream bandwidth grant is used to controlthe ONU to send upstream data on the first upstream channel, and thesecond upstream bandwidth grant is used to control the ONU to sendupstream data on the second upstream channel.

Embodiment 14

The OLT according to embodiment 13, wherein the OLT comprises a firstDBA scheduling module, a second DBA scheduling module, and amultiplexing module, wherein the first DBA scheduling module isconfigured to generate the first upstream bandwidth grant; the secondDBA scheduling module is configured to generate the second upstreambandwidth grant; the multiplexing module is connected to the first DBAscheduling module and the second DBA scheduling module, and isconfigured to multiplex the first upstream bandwidth grant and thesecond upstream bandwidth grant; and the multiplexing module is furtherconnected to the downstream TC module, and is configured to provide themultiplexed upstream bandwidth grant for the downstream TC module.

Embodiment 15

The OLT according to embodiment 14, wherein the first upstream channelis used to transmit upstream service data, and the second upstreamchannel is used to transmit a registration response packet; the firstDBA scheduling module is configured to generate the first upstreambandwidth grant comprising an upstream sending timeslot; and the secondDBA scheduling module is configured to generate the second upstreambandwidth grant comprising a registration timeslot, wherein the upstreamsending timeslot is used to instruct the registered ONU to send theupstream service data on the first upstream channel, and theregistration timeslot is used to instruct the unregistered ONU to sendthe registration response packet on the second upstream channel.

Embodiment 16

The OLT according to embodiment 14, wherein the first upstream channelis used to transmit first upstream service data, the second upstreamchannel is used to transmit a registration response packet and secondupstream service data, and a delay requirement of the first upstreamservice data is higher than a delay requirement of the second upstreamservice data; the first DBA scheduling module is configured to generatethe first upstream bandwidth grant comprising a first upstream sendingtimeslot; and the second DBA scheduling module is configured to generatethe second upstream bandwidth grant comprising a second upstream sendingtimeslot and a registration timeslot, wherein the first upstream sendingtimeslot is used to instruct the registered ONU to send the firstupstream service data on the first upstream channel, the second upstreamsending timeslot is used to instruct the registered ONU to send thesecond upstream service data on the second upstream channel, theregistration timeslot is used to instruct the unregistered ONU to sendthe registration response packet on the second upstream channel.

Embodiment 17

The OLT according to any one of embodiments 14 to 16, wherein the OLTfurther comprises a control module, and the control module is connectedto the first DBA scheduling module and the second DBA scheduling module;and the control module is configured to: control the first DBAscheduling module to disable the registration function, and control thesecond DBA scheduling module to enable the registration function,wherein the second upstream bandwidth grant generated by the second DBAscheduling module that enables the registration function comprises theregistration timeslot, and the registration timeslot is used to instructthe unregistered ONU to send the registration response packet on thesecond upstream channel.

Embodiment 18

The OLT according to embodiment 13, wherein the OLT comprises one DBAscheduling module and a control module connected to the DBA schedulingmodule; the control module is configured to control the DBA schedulingmodule to enable or disable the registration function; when disablingthe registration function, the DBA scheduling module is configured to:generate the first upstream bandwidth grant comprising a first upstreamsending timeslot, or generate the first upstream bandwidth grantcomprising the first upstream sending timeslot and the second upstreambandwidth grant comprising a second upstream sending timeslot; and whenenabling the registration function, the DBA scheduling module is furtherconfigured to generate the first upstream bandwidth grant comprising thefirst upstream sending timeslot and the second upstream bandwidth grantcomprising a registration timeslot, wherein the first upstream sendingtimeslot is used to instruct the registered ONU to send the firstupstream service data on the first upstream channel, the second upstreamsending timeslot is used to instruct the registered ONU to send thesecond upstream service data on the second upstream channel, a delayrequirement of the first upstream service data is higher than a delayrequirement of the second upstream service data, and the registrationtimeslot is used to instruct the unregistered ONU to send a registrationresponse packet on the second upstream channel.

Embodiment 19

The OLT according to any one of embodiments 12 to 18, wherein the OLTfurther comprises a memory; the memory is connected to each DBAscheduling module, and is configured to store the upstream bandwidthgrant generated by each DBA scheduling module; and the upstream TCmodule is connected to the memory, and is configured to: control, basedon the upstream bandwidth grant, the first upstream burst receiver andthe second upstream burst receiver to receive the upstream data, and/orperform, based on the upstream bandwidth grant, authentication andparsing on the upstream data sent by each ONU.

Embodiment 20

The OLT according to any one of embodiments 12 to 19, wherein if the OLTis used in a gigabit-capable passive optical network (GPON) system, abandwidth map (BWmap) message carries the upstream bandwidth grant; orif the OLT is used in an Ethernet passive optical network EPON system, aGate message carries the upstream bandwidth grant.

Embodiment 21

The OLT according to embodiment 20, wherein when the BWmap messagecarries the upstream bandwidth grant, a predetermined bit of apredetermined field in the BWmap message is used to identify an upstreamchannel corresponding to the BWmap message; and when the Gate messagecarries the upstream bandwidth grant, a channel identifier field newlyadded to the Gate message is used to identify an upstream channelcorresponding to the Gate message, or operation code of the Gate messageis used to identify an upstream channel corresponding to the Gatemessage, wherein the predetermined field is a start time field or agrant size field, and the predetermined bit is one most significant bitor two most significant bits of the predetermined field.

Embodiment 22

The OLT according to any one of embodiments 12 to 19, wherein thedownstream channel, the first upstream channel, and the second upstreamchannel share one optical distribution network (ODN) in a wavelengthdivision multiplexing manner, and wavelengths of the first upstreamchannel and the second upstream channel are different.

Embodiment 23

An optical network unit (ONU), wherein the ONU comprises: a downstreamtransmission convergence (TC) module, at least one dynamic bandwidthallocation (DBA) response module, an upstream TC module, a downstreamreceiver, a first upstream burst transmitter, and a second upstreamburst transmitter, wherein the downstream TC module is connected to thedownstream receiver and the DBA response module, and is configured toprovide, for the DBA response module, downstream data received by thedownstream receiver on a downstream channel, wherein the downstream datais sent by an optical line terminal (OLT); the DBA response module isconnected to the upstream TC module, and is configured to control, basedon an upstream bandwidth grant comprised in the downstream data, theupstream TC module to send upstream data; the upstream TC module isconnected to the first upstream burst transmitter, and is configured tosend the upstream data on a first upstream channel by using the firstupstream burst transmitter; and the upstream TC module is connected tothe second upstream burst transmitter, and is configured to send theupstream data on a second upstream channel by using the second upstreamburst transmitter, wherein a registration function is disabled on thefirst upstream channel, the registration function is enabled on thesecond upstream channel, and the registration function is used toregister the unregistered ONU.

Embodiment 24

The ONU according to embodiment 23, wherein the downstream datacomprises a first upstream bandwidth grant and a second upstreambandwidth grant, the first upstream bandwidth grant is used to controlthe ONU to send upstream data on the first upstream channel, and thesecond upstream bandwidth grant is used to control the ONU to sendupstream data on the second upstream channel.

Embodiment 25

The ONU according to embodiment 24, wherein the ONU comprises a firstDBA response module, a second DBA response module, and a demultiplexingmodule, wherein the demultiplexing module is connected to the downstreamTC module, and is configured to demultiplex the upstream bandwidth grantreceived by the downstream TC module, to obtain the first upstreambandwidth grant and the second upstream bandwidth grant; the first DBAresponse module is connected to the demultiplexing module, and isconfigured to control, based on the first upstream bandwidth grant, theupstream TC module to send the upstream data on the first upstreamchannel; and the second DBA response module is connected to thedemultiplexing module, and is configured to control, based on the secondupstream bandwidth grant, the upstream TC module to send the upstreamdata on the second upstream channel.

Embodiment 26

The ONU according to embodiment 25, wherein the first upstream channelis used to transmit upstream service data, and the second upstreamchannel is used to transmit a registration response packet; if the ONUis in a registered state, the upstream TC module is configured to send afirst enabling signal to the first upstream burst transmitter based onan upstream sending timeslot in the first upstream bandwidth grant,wherein the first enabling signal is used to instruct the first upstreamburst transmitter to send the upstream service data on the firstupstream channel; and if the ONU is in an unregistered state, theupstream TC module is configured to send a second enabling signal to thesecond upstream burst transmitter based on a registration timeslot inthe second upstream bandwidth grant, wherein the second enabling signalis used to instruct the second upstream burst transmitter to send theregistration response packet on the second upstream channel.

Embodiment 27

The ONU according to embodiment 25 or 26, wherein the ONU comprises anoptical module slot, and the optical module slot is used for a firstoptical module or a second optical module to slot into; the firstoptical module comprises at least the downstream receiver and the firstupstream burst transmitter; and the second optical module comprises atleast the downstream receiver and the second upstream burst transmitter,wherein when the ONU is in the unregistered state, the second opticalmodule is slot into the optical module slot; or when the ONU is in theregistered state, the first optical module is slot into the opticalmodule slot.

Embodiment 28

The ONU according to embodiment 25, wherein the first upstream channelis used to transmit first upstream service data, the second upstreamchannel is used to transmit a registration response packet and secondupstream service data, and a delay requirement of the first upstreamservice data is higher than a delay requirement of the second upstreamservice data; if the ONU is in a registered state, the upstream TCmodule is configured to: send a third enabling signal to the firstupstream burst transmitter based on a first upstream sending timeslot inthe first upstream bandwidth grant, wherein the third enabling signal isused to instruct the first upstream burst transmitter to send the firstupstream service data on the first upstream channel; and send a fourthenabling signal to the second upstream burst transmitter based on asecond upstream sending timeslot in the second upstream bandwidth grant,wherein the fourth enabling signal is used to instruct the secondupstream burst transmitter to send the second upstream service data onthe second upstream channel; and if the ONU is in an unregistered state,the upstream TC module is configured to send a fifth enabling signal tothe second upstream burst transmitter based on a registration timeslotin the second upstream bandwidth grant, wherein the fifth enablingsignal is used to instruct the second upstream burst transmitter to sendthe registration response packet on the second upstream channel.

Embodiment 29

The ONU according to embodiment 27, wherein the ONU further comprises aservice classification module; the service classification module isconfigured to: collect a delay requirement of each service and determinea service class of the service based on the delay requirement; the DBAresponse module is connected to the service classification module, andis configured to: when the service class indicates that the servicebelongs to a first class, control the upstream TC module to send, on thefirst upstream channel, first upstream service data corresponding to theservice; and the DBA response module is further configured to: when theservice class indicates that the service belongs to a second class,control the upstream TC module to send, on the second upstream channel,second upstream service data corresponding to the service.

Embodiment 30

The ONU according to embodiment 28 or 29, wherein the ONU comprises afirst optical module slot and a second optical module slot, the firstoptical module slot is used for the first optical module to slot into,and the second optical module slot is used for the second optical moduleto slot into; the first optical module comprises at least the firstupstream burst transmitter; and the second optical module comprises atleast the downstream receiver and the second upstream burst transmitter,wherein when the second upstream service data is transmitted, the secondoptical module is slot into the second optical module slot; and when thefirst upstream service data and the second upstream service data aretransmitted, the second optical module is slot into the second opticalmodule slot and the first optical module is slot into the first opticalmodule slot.

Embodiment 31

The ONU according to embodiment 24, wherein the ONU comprises one DBAresponse module and a channel selection module; the channel selectionmodule is connected to the first upstream burst transmitter, the secondupstream burst transmitter, and the upstream TC module; the DBA responsemodule is configured to: control, based on the first upstream bandwidthgrant, the upstream TC module to send upstream service data, or control,based on the second upstream bandwidth grant, the upstream TC module tosend a registration response packet; and the channel selection module isconfigured to: when the ONU is in a registered state, select the firstupstream burst transmitter to send the upstream service data generatedby the upstream TC module, or when the ONU is in an unregistered state,select the second upstream burst transmitter to send the registrationresponse packet generated by the upstream TC module.

Embodiment 32

The ONU according to any one of embodiments 23 to 31, wherein if the ONUis used in a gigabit-capable passive optical network (GPON) system, abandwidth map (BWmap) message carries the upstream bandwidth grant; orif the ONU is used in an Ethernet passive optical network EPON system, aGate message carries the upstream bandwidth grant.

Embodiment 33

The ONU according to embodiment 32, wherein when the BWmap messagecarries the upstream bandwidth grant, a predetermined bit of apredetermined field in the BWmap message is used to identify an upstreamchannel corresponding to the BWmap message; and when the Gate messagecarries the upstream bandwidth grant, a channel identifier field newlyadded to the Gate message is used to identify an upstream channelcorresponding to the Gate message, or operation code of the Gate messageis used to identify an upstream channel corresponding to the Gatemessage, wherein the predetermined field is a start time field or agrant size field, and the predetermined bit is one most significant bitor two most significant bits of the predetermined field.

Embodiment 34

The ONU according to any one of embodiments 23 to 31, wherein thedownstream channel, the first upstream channel, and the second upstreamchannel share one optical distribution network (ODN) in a wavelengthdivision multiplexing manner, and wavelengths of the first upstreamchannel and the second upstream channel are different.

The sequence numbers of the foregoing embodiments of this applicationare merely for illustrative purposes, and are not intended to indicatepriorities of the embodiments.

A person of ordinary skill in the art may understand that all or some ofthe steps of the embodiments may be implemented by hardware or a programinstructing related hardware. The program may be stored in acomputer-readable storage medium. The storage medium may include: aread-only memory, a magnetic disk, an optical disc, or the like.

The foregoing descriptions are merely specific embodiments of thisapplication, but are not intended to limit this application. Anymodification, equivalent replacement, or improvement made withoutdeparting from the spirit and principle of this application shall fallwithin the protection scope of this application.

What is claimed is:
 1. A method, comprising: receiving, by an opticalnetwork unit (ONU), a second upstream bandwidth grant sent by an opticalline terminal (OLT) on a downstream channel, wherein the second upstreambandwidth grant indicates information for the ONU to send a registrationresponse packet on a second upstream channel; sending, by the ONU, theregistration response packet to the OLT on the second upstream channel;receiving on the downstream channel, by the ONU, a first upstreambandwidth grant indicating information for the ONU to send a firstupstream service data on a first upstream channel and a third upstreambandwidth grant indicating information for the ONU to send a secondupstream service data on the second upstream channel; and sending, bythe ONU, the first upstream service data to the OLT on the firstupstream channel and the second upstream service data to the OLT on thesecond upstream channel; wherein a wavelength of the first upstreamchannel is not equal to a wavelength of the second upstream channel. 2.The method according to claim 1, wherein the second upstream bandwidthgrant comprises a registration timeslot; wherein the sending, by theONU, the registration response packet to the OLT on the second upstreamchannel comprises: sending, by the ONU, the registration response packetto the OLT on the second upstream channel based on the registrationtimeslot in the second upstream bandwidth grant.
 3. The method accordingto claim 2, wherein the first upstream bandwidth grant comprises a firstupstream sending timeslot, and wherein the third upstream bandwidthgrant further comprises a second upstream sending timeslot; whereinsending, by the ONU, the first upstream service data to the OLT on thefirst upstream channel and the second upstream service data to the OLTon the second upstream channel comprises: sending, by the ONU, the firstupstream service data to the OLT on the first upstream channel based onthe first upstream sending timeslot in the first upstream bandwidthgrant and the second upstream service data to the OLT on the secondupstream channel based on the second upstream sending timeslot in thethird upstream bandwidth grant.
 4. The method according to claim 1,wherein the ONU and the OLT exchange data on one downstream channel andtwo upstream channels, and wherein the two upstream channels comprisethe first upstream channel and the second upstream channel.
 5. Themethod according to claim 1, wherein a delay requirement of the firstupstream service data is higher than a delay requirement of the secondupstream service data.
 6. A method, comprising: sending, by an opticalline terminal (OLT), a second upstream bandwidth grant to an opticalnetwork unit (ONU) on a downstream channel, wherein the second upstreambandwidth grant indicates information for the ONU to send a registrationresponse packet on a second upstream channel; receiving, by the OLT, theregistration response packet sent by the ONU on the second upstreamchannel; sending on the downstream channel, by the OLT, a first upstreambandwidth grant indicating information for the ONU to send a firstupstream service data on a first upstream channel and a third upstreambandwidth grant indicating information for the ONU to send a secondupstream service data on the second upstream channel; and receiving, bythe OLT, the first upstream service data on the first upstream channeland the second upstream service data on the second upstream channel sentby the ONU; wherein a wavelength of the first upstream channel is notequal to a wavelength of the second upstream channel.
 7. The methodaccording to claim 6, wherein the method further comprises: generating,by the OLT, the first upstream bandwidth grant, the second upstreambandwidth grant, and the third upstream bandwidth grant; wherein thefirst upstream bandwidth grant comprises a first upstream sendingtimeslot; wherein the second upstream bandwidth grant comprises aregistration timeslot; and wherein the third upstream bandwidth grantcomprises a second upstream sending timeslot.
 8. The method according toclaim 6, wherein the OLT and the ONU exchange data on one downstreamchannel and two upstream channels, and wherein the two upstream channelscomprise the first upstream channel and the second upstream channel. 9.The method according to claim 6, wherein a delay requirement of thefirst upstream service data is higher than a delay requirement of thesecond upstream service data.
 10. An optical network unit (ONU), whereinthe ONU comprises: a downstream receiver, a first upstream bursttransmitter, and a second upstream burst transmitter; wherein thedownstream receiver is configured to receive a second upstream bandwidthgrant sent by an optical line terminal (OLT) on a downstream channel,wherein the second upstream bandwidth grant indicates information forthe ONU to send a registration response packet on a second upstreamchannel; wherein the second upstream burst transmitter is configured tosend the registration response packet to the OLT on the second upstreamchannel; wherein the downstream receiver is further configured toreceive a first upstream bandwidth grant sent by the OLT on thedownstream channel, wherein the first upstream bandwidth grant indicatesinformation for the ONU to send a first upstream service data on a firstupstream channel; wherein the first upstream burst transmitter isconfigured to send the first upstream service data to the OLT on thefirst upstream channel; wherein the downstream receiver is furtherconfigured to receive a third upstream bandwidth grant indicatinginformation for the ONU to send a second upstream service data on thesecond upstream channel; wherein the second upstream burst transmitteris further configured to send the second upstream service data to theOLT on the second upstream channel; and wherein a wavelength of thefirst upstream channel is not equal to a wavelength of the secondupstream channel.
 11. The ONU according to claim 10, wherein the secondupstream bandwidth grant comprises a registration timeslot; and whereinthe second upstream burst transmitter is configured to send theregistration response packet to the OLT on the second upstream channelbased on the registration timeslot in the second upstream bandwidthgrant.
 12. The ONU according to claim 11, wherein the first upstreambandwidth grant comprises a first upstream sending timeslot, and whereinthe third upstream bandwidth grant further comprises a second upstreamsending timeslot; wherein the first upstream burst transmitter isfurther configured to send the first upstream service data to the OLT onthe first upstream channel based on the first upstream sending timeslotin the first upstream bandwidth grant, and wherein the second upstreamburst transmitter is further configured to send the second upstreamservice data to the OLT on the second upstream channel based on thesecond upstream sending timeslot in the third upstream bandwidth grant.13. The ONU according to claim 10, wherein the ONU and the OLT exchangedata on one downstream channel and two upstream channels, and whereinthe two upstream channels comprise the first upstream channel and thesecond upstream channel.
 14. The ONU according to claim 10, wherein adelay requirement of the first upstream service data is higher than adelay requirement of the second upstream service data.
 15. An opticalline terminal (OLT), wherein the OLT comprises: a downstreamtransmitter, a first upstream burst receiver, and a second upstreamburst receiver; wherein the downstream transmitter is configured to senda second upstream bandwidth grant to an optical network unit (ONU) on adownstream channel, wherein the second upstream bandwidth grantindicates information for the ONU to send a registration response packeton a second upstream channel; wherein the second upstream burst receiveris configured to receive the registration response packet sent by theONU on the second upstream channel; wherein the downstream transmitteris further configured to send a first upstream bandwidth grant to theONU on the downstream channel, wherein the first upstream bandwidthgrant indicates information for the ONU to send a first upstream servicedata on a first upstream channel; wherein the first upstream burstreceiver is configured to receive the first upstream service data on thefirst upstream channel; wherein the downstream transmitter is furtherconfigured to send a third upstream bandwidth grant indicatinginformation for the ONU to send a second upstream service data on thesecond upstream channel; wherein the second upstream burst receiver isfurther configured to receive the second upstream service data on thesecond upstream channel sent by the ONU; and wherein a wavelength of thefirst upstream channel is not equal to a wavelength of the secondupstream channel.
 16. The OLT according to claim 15, wherein the OLT andthe ONU exchange data on one downstream channel and two upstreamchannels, and wherein the two upstream channels comprise the firstupstream channel and the second upstream channel.
 17. The OLT accordingto claim 15, wherein a delay requirement of the first upstream servicedata is higher than a delay requirement of the second upstream servicedata.
 18. A passive optical network (PON) system, wherein the systemcomprises: an optical line terminal (OLT) and an optical network unit(ONU); wherein the OLT is configured to send a second upstream bandwidthgrant to the ONU on a downstream channel, wherein the second upstreambandwidth grant indicates information for the ONU to send a registrationresponse packet on a second upstream channel; wherein the ONU isconfigured to receive the second upstream bandwidth grant on thedownstream channel and send the registration response packet to the OLTon the second upstream channel; wherein the OLT is further configured toreceive the registration response packet on the second upstream channel;wherein the OLT is further configured to send a first upstream bandwidthgrant to the ONU on the downstream channel, wherein the first upstreambandwidth grant indicates information for the ONU to send a firstupstream service data on a first upstream channel, wherein a wavelengthof the first upstream channel is not equal to a wavelength of the secondupstream channel; wherein the ONU is further configured to receive thefirst upstream bandwidth grant on the downstream channel and send thefirst upstream service data to the OLT on the first upstream channel;wherein the OLT is further configured to receive the first upstreamservice data on the first upstream channel; wherein the OLT is furtherconfigured to send a third upstream bandwidth grant indicatinginformation for the ONU to send a second upstream service data on thesecond upstream channel; wherein the ONU is further configured toreceive the second upstream bandwidth grant on the downstream channeland send the second upstream service data to the OLT on the secondupstream channel; and wherein the OLT is further configured to receivethe second upstream service data on the second upstream channel sent bythe ONU.
 19. The PON system according to claim 18, wherein the OLT andthe ONU exchange data on one downstream channel and two upstreamchannels, and wherein the two upstream channels comprise the firstupstream channel and the second upstream channel.
 20. The PON systemaccording to claim 18, wherein a delay requirement of the first upstreamservice data is higher than a delay requirement of the second upstreamservice data.